[MC-33383] Lag while taking screenshot with F2 in singleplayer

The bug

While taking a screenshot using the in-game F2 key, the game freezes for a second and does not take an accurate screenshot.

Code analysis

The reason why this is happening is because saving the screenshot is not done by a seperate thread. This means the lag time is determined by the writing speed of your harddrive.

Another reason which has probably a rather small impact is that in case frame buffering is enabled Minecraft iterates over all pixels in the screenshot and sets them in a BufferedImage. I do not see any advantage of this.
Here is a "fix" that solves this problem, however the ScreenshotSavingThread is only used as a local variable to demonstrate that it solves the problem. It should be rather in the class itself and also set the error message in case it fails:
saveScreenshot(File p_148259_0_, String p_148259_1_, int p_148259_2_, int p_148259_3_, Framebuffer p_148259_4_) method of the net.minecraft.util.ScreenShotHelper class (MCP 1.8 names)

saveScreenshot(File p_148259_0_, String p_148259_1_, int p_148259_2_, int p_148259_3_, Framebuffer p_148259_4_)

// Is there any advantage from this?
if (OpenGlHelper.isFramebufferEnabled())
{
	var7 = new BufferedImage(p_148259_4_.framebufferWidth, p_148259_4_.framebufferHeight, 1);
	int var8 = p_148259_4_.framebufferTextureHeight - p_148259_4_.framebufferHeight;

	for (int var9 = var8; var9 < p_148259_4_.framebufferTextureHeight; ++var9)
	{
		for (int var10 = 0; var10 < p_148259_4_.framebufferWidth; ++var10)
		{
			var7.setRGB(var10, var9 - var8, pixelValues[var9 * p_148259_4_.framebufferTextureWidth + var10]);
		}
	}
}
else
{
	var7 = new BufferedImage(p_148259_2_, p_148259_3_, 1);
	var7.setRGB(0, 0, p_148259_2_, p_148259_3_, pixelValues, 0, p_148259_2_);
}

File var12;

if (p_148259_1_ == null)
{
	var12 = getTimestampedPNGFileForDirectory(var5);
}
else
{
	var12 = new File(var5, p_148259_1_);
}

// Create an empty file to make sure a ScreenshotSavingThreads do not override it by accident
var12.createNewFile();

//ImageIO.write(var7, "png", var12);
class ScreenshotSavingThread extends Thread {
	private final BufferedImage bufferedImage;
	private final File file;
	
	private ScreenshotSavingThread(BufferedImage bufferedImage, File file) {
		this.bufferedImage = bufferedImage;
		this.file = file;
	}
	
	@Override
	public void run() {
		try {
			ImageIO.write(bufferedImage, "png", file);
		} catch (IOException e) {
			// TODO Print the error message in chat and in the log
		}
	}
}
new ScreenshotSavingThread(var7, var12).start();

Flaws with this design

Stopping Minecraft could cause half-finished screenshots (unlikely); thread could be non-daemon
Taking screenshots to often results in a OutOfMemoryError (unlikely, that would need with 500KB per screenshot and 500MB allocated RAM about 1000 ScreenshotSavingThreads running at once)
Reporting error or success would have to be synchronized and would appear delayed which could be confusing

Linked issues

is duplicated by 1

MC-62470 Lag "Spikes" when taking screenshots Resolved

Attachments

Dev Console Output.txt

screenshot_2.txt

Comments 23

kumasasa 2013-10-01T20:09:44Z

Please attach the complete output of the "Development console" tab of the launcher.

Click the text, press CTRL-A to select all, then CTRL-C to copy, and CTRL-V to paste in a comment on this ticket.

Andrew Thomas 2013-10-03T13:45:00Z

There you go. It's uploaded as a .txt so it doesn't take up tons of space.

kumasasa 2013-10-03T14:21:34Z

You have not Internet on that computer or Minecraft is blocked to reach the Internet:

Client> 22:18:10.817 [MCO Availability Checker #1] ERROR bpm - Couldn't connect to Realms
Client> 22:18:27.537 [Skin downloader: http://skins.minecraft.net/MinecraftCloaks/greatmastermario.png] ERROR bmj - Couldn't download http texture

Does it lag too if you have an internet connection ?

Andrew Thomas 2013-10-05T01:58:34Z

This is today for 1.6.4 and then 13w39b with internet access.

It did not lag as much in the snapshot as 1.6, but it was still significant. No change internet vs no internet.

Launcher 1.2.5 (through bootstrap 5) started on windows...
Current time is Oct 4, 2013 6:54:16 PM
System.getProperty('os.name') == 'Windows 8'
System.getProperty('os.version') == '6.2'
System.getProperty('os.arch') == 'amd64'
System.getProperty('java.version') == '1.7.0_25'
System.getProperty('java.vendor') == 'Oracle Corporation'
System.getProperty('sun.arch.data.model') == '64'
Refreshing local version list...
Refreshing remote version list...
Refresh complete.
Loaded 5 profile(s); selected 'greatmastermario'
Refreshing auth...
Logging in with access token
Getting syncinfo for selected version
Queueing library & version downloads
Download job 'Version & Libraries' started (8 threads, 19 files)
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput-platform\2.0.5\jinput-platform-2.0.5-natives-windows.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\argo\argo\2.25_fixed\argo-2.25_fixed.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.0\lwjgl-platform-2.9.0-natives-windows.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4.jar for job 'Version & Libraries': Used own copy as it matched etag
Job 'Version & Libraries' finished successfully
Delta time to compare resources: 5592 ms 
Download job 'Resources' skipped as there are no files to download
Job 'Resources' finished successfully
Launching game
Looking for old natives to clean up...
Unpacking natives to C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4-natives-283797157718033
Launching in C:\Users\Andrew\AppData\Roaming\.minecraft
Running C:\Program Files\Java\jre7\bin\javaw.exe -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -Djava.library.path=C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4-natives-283797157718033 -cp C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\argo\argo\2.25_fixed\argo-2.25_fixed.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4.jar net.minecraft.client.main.Main --username greatmastermario --session token:2f6f7b3f703c421ea81000fc58a65aa1:d4a0aadfbec94ab29dce03f396744279 --version 1.6.4 --gameDir C:\Users\Andrew\AppData\Roaming\.minecraft --assetsDir C:\Users\Andrew\AppData\Roaming\.minecraft\assets
Client> 2013-10-04 18:54:28 [CLIENT] [INFO] Setting user: greatmastermario
Client> 2013-10-04 18:54:29 [CLIENT] [INFO] (Session ID is token:2f6f7b3f703c421ea81000fc58a65aa1:d4a0aadfbec94ab29dce03f396744279)
Client> 2013-10-04 18:54:29 [CLIENT] [INFO] LWJGL Version: 2.9.0
Client> 2013-10-04 18:54:30 [CLIENT] [INFO] Reloading ResourceManager: Default
Client> 
Client> Starting up SoundSystem...
Client> Initializing LWJGL OpenAL
Client>     (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
Client> OpenAL initialized.
Client> 
Client> 2013-10-04 18:54:37 [SERVER] [INFO] Starting integrated minecraft server version 1.6.4
Client> 2013-10-04 18:54:37 [SERVER] [INFO] Generating keypair
Client> 2013-10-04 18:54:37 [SERVER] [INFO] Preparing start region for level 0
Client> 2013-10-04 18:54:38 [SERVER] [INFO] Preparing spawn area: 4%
Client> 2013-10-04 18:54:39 [SERVER] [INFO] Preparing spawn area: 32%
Client> 2013-10-04 18:54:40 [SERVER] [INFO] Preparing spawn area: 69%
Client> 2013-10-04 18:54:41 [SERVER] [INFO] Preparing spawn area: 88%
Client> 2013-10-04 18:54:41 [SERVER] [SEVERE] Item entity 230 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at net.minecraft.server.MinecraftServer.f(SourceFile:230)
Client> 	at bkz.a(SourceFile:90)
Client> 	at bkz.d(SourceFile:106)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:315)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 11 more
Client> loading single player
Client> 2013-10-04 18:54:42 [SERVER] [INFO] greatmastermario[/127.0.0.1:0] logged in with entity id 274 at (142.75738770890987, 11.0, 241.2320973001016)
Client> 2013-10-04 18:54:42 [SERVER] [INFO] greatmastermario joined the game
Client> 2013-10-04 18:54:42 [SERVER] [SEVERE] Item entity 391 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> Setting up custom skins
Client> 2013-10-04 18:54:43 [SERVER] [SEVERE] Item entity 407 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> 2013-10-04 18:54:43 [SERVER] [SEVERE] Item entity 408 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> 2013-10-04 18:54:44 [SERVER] [INFO] Saving and pausing game...
Client> 2013-10-04 18:54:44 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Overworld
Client> 2013-10-04 18:54:44 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Nether
Client> 2013-10-04 18:54:44 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/The End
Client> 2013-10-04 18:54:47 [SERVER] [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
Client> 2013-10-04 18:54:58 [CLIENT] [INFO] [CHAT] Saved screenshot as 2013-10-04_18.54.57.png
Client> 2013-10-04 18:54:59 [SERVER] [INFO] Saving and pausing game...
Client> 2013-10-04 18:54:59 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Overworld
Client> 2013-10-04 18:54:59 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Nether
Client> 2013-10-04 18:54:59 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/The End
Client> 2013-10-04 18:55:00 [SERVER] [INFO] greatmastermario lost connection: disconnect.quitting
Client> 2013-10-04 18:55:00 [SERVER] [INFO] greatmastermario left the game
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Stopping singleplayer server as player logged out
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Stopping server
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Saving players
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Saving worlds
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Overworld
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/Nether
Client> 2013-10-04 18:55:00 [SERVER] [INFO] Saving chunks for level 'Snapshot for Idiots'/The End
Client> 2013-10-04 18:55:02 [CLIENT] [INFO] Stopping!
Client> 
Client> SoundSystem shutting down...
Client>     Author: Paul Lamb, www.paulscode.com
Client> 
Game ended with no troubles detected (exit code 0)
Following visibility rule and showing launcher as the game has ended
Deleting C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4-natives-283797157718033
Couldn't delete C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4-natives-283797157718033 - scheduling for deletion upon exit
Deleting C:\Users\Andrew\AppData\Roaming\.minecraft\versions\1.6.4\1.6.4-natives-283797157718033
Getting syncinfo for selected version
Queueing library & version downloads
Download job 'Version & Libraries' started (8 threads, 24 files)
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\java3d\vecmath\1.3.1\vecmath-1.3.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput-platform\2.0.5\jinput-platform-2.0.5-natives-windows.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\trove4j\trove4j\3.0.3\trove4j-3.0.3.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.0\lwjgl-platform-2.9.0-natives-windows.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\mojang\authlib\1.1\authlib-1.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b.jar for job 'Version & Libraries': Used own copy as it matched etag
Job 'Version & Libraries' finished successfully
Launching game
Looking for old natives to clean up...
Unpacking natives to C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b-natives-283915059862583
Launching in C:\Users\Andrew\AppData\Roaming\.minecraft
Running C:\Program Files\Java\jre7\bin\javaw.exe -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G -Djava.library.path=C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b-natives-283915059862583 -cp C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\java3d\vecmath\1.3.1\vecmath-1.3.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\trove4j\trove4j\3.0.3\trove4j-3.0.3.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\com\mojang\authlib\1.1\authlib-1.1.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar;C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b.jar net.minecraft.client.main.Main --username greatmastermario --session token:2f6f7b3f703c421ea81000fc58a65aa1:d4a0aadfbec94ab29dce03f396744279 --version 13w39b --gameDir C:\Users\Andrew\AppData\Roaming\.minecraft --assetsDir C:\Users\Andrew\AppData\Roaming\.minecraft\assets --uuid d4a0aadfbec94ab29dce03f396744279 --accessToken 2f6f7b3f703c421ea81000fc58a65aa1
Client> 
Client> Starting up SoundSystem...
Client> Initializing LWJGL OpenAL
Client>     (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
Client> OpenAL initialized.
Client> 
Client> 
Client> SoundSystem shutting down...
Client>     Author: Paul Lamb, www.paulscode.com
Client> 
Game ended with no troubles detected (exit code 0)
Following visibility rule and showing launcher as the game has ended
Deleting C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b-natives-283915059862583
Couldn't delete C:\Users\Andrew\AppData\Roaming\.minecraft\versions\13w39b\13w39b-natives-283915059862583 - scheduling for deletion upon exit

kumasasa 2013-10-05T20:13:26Z

Your world file is corrupted:

Client> 2013-10-04 18:54:41 [SERVER] [INFO] Preparing spawn area: 88%
Client> 2013-10-04 18:54:41 [SERVER] [SEVERE] Item entity 230 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at net.minecraft.server.MinecraftServer.f(SourceFile:230)
Client> 	at bkz.a(SourceFile:90)
Client> 	at bkz.d(SourceFile:106)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:315)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 11 more
Client> loading single player
Client> 2013-10-04 18:54:42 [SERVER] [INFO] greatmastermario[/127.0.0.1:0] logged in with entity id 274 at (142.75738770890987, 11.0, 241.2320973001016)
Client> 2013-10-04 18:54:42 [SERVER] [INFO] greatmastermario joined the game
Client> 2013-10-04 18:54:42 [SERVER] [SEVERE] Item entity 391 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> Setting up custom skins
Client> 2013-10-04 18:54:43 [SERVER] [SEVERE] Item entity 407 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> 2013-10-04 18:54:43 [SERVER] [SEVERE] Item entity 408 has no item?!
Client> u: Loading entity NBT
Client> 	at nn.f(SourceFile:1069)
Client> 	at nt.a(SourceFile:148)
Client> 	at aee.a(SourceFile:280)
Client> 	at aee.a(SourceFile:73)
Client> 	at aee.a(SourceFile:61)
Client> 	at jr.f(SourceFile:127)
Client> 	at jr.c(SourceFile:78)
Client> 	at jq.<init>(SourceFile:29)
Client> 	at jp.a(SourceFile:208)
Client> 	at jp.a(SourceFile:240)
Client> 	at hn.a(SourceFile:141)
Client> 	at hn.c(SourceFile:188)
Client> 	at hn.a(SourceFile:85)
Client> 	at blc.b(SourceFile:73)
Client> 	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
Client> 	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
Client> 	at bkz.s(SourceFile:124)
Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
Client> 	at hi.run(SourceFile:583)
Client> Caused by: java.lang.NullPointerException
Client> 	at oo.b(SourceFile:129)
Client> 	at ss.a(SourceFile:229)
Client> 	at ss.a(SourceFile:179)
Client> 	at nn.f(SourceFile:1062)
Client> 	... 18 more
Client> 2013-10-04 18:54:47 [SERVER] [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
Client> 2013-10-04 18:54:58 [CLIENT] [INFO] [CHAT] Saved screenshot as 2013-10-04_18.54.57.png

13 more comments

kumasasa 2013-10-09T21:02:19Z

Can you repeat that lag while screenshotting with a new created world ?

Andrew Thomas 2013-10-11T02:04:57Z

Here is a completely new save I created just for this purpose in 13w41a. Still lags for about 1 second before continuing.

Andrew Thomas 2013-10-11T15:03:59Z

Need to add 1.6.4 and 13w41a to "Affects Version"

Ezekiel 2013-11-27T20:16:58Z

Is this still a concern in the latest Minecraft version 13w48b? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Ezekiel 2014-01-15T18:09:35Z

This ticket is incomplete without the requested information, no response has been received within a reasonable time and we are assuming the issue has been resolved. If you are still experiencing this issue, we can reopen it at your request.
Please review the guidelines before reporting issues.

marcono1234 2014-09-28T19:50:42Z

Confirmed for

1.8 also right after the lag, the framerate is at around 20 (normally 80) added screenshots
1.8.2-pre1 In the F3 screen you can even see how it shows sometimes 0 FPS after the screenshot
1.8.3

marcono1234 2014-10-16T15:05:58Z

Like I said, confirmed for 1.8

Erik Broes 2015-11-09T10:58:12Z

You go pixelate 2,015,640 pixels fast in paint!

marcono1234 2015-12-20T20:38:10Z

But it seems to happen not for everyone, does it?

marcono1234 2015-12-24T12:49:41Z

Confirmed for

15w51b

This is definitely a valid report. The reason why this is happening is because saving the screenshot is not done by a seperate thread. This means the lag time is determined by the writing speed of your harddrive.

Another reason which has probably a rather small impact is that in case frame buffering is enabled Minecraft iterates over all pixels in the screenshot and sets them in a BufferedImage. I do not see any advantage of this.
Here is a "fix" that solves this problem, however the ScreenshotSavingThread is only use as a local variable to demonstrate that it solves the problem. It should be rather in the class itself and also set the error message in case it fails:
saveScreenshot(File p_148259_0_, String p_148259_1_, int p_148259_2_, int p_148259_3_, Framebuffer p_148259_4_) method of the net.minecraft.util.ScreenShotHelper class (MCP 1.8 names)

saveScreenshot(File p_148259_0_, String p_148259_1_, int p_148259_2_, int p_148259_3_, Framebuffer p_148259_4_)

// Is there any advantage from this?
if (OpenGlHelper.isFramebufferEnabled())
{
	var7 = new BufferedImage(p_148259_4_.framebufferWidth, p_148259_4_.framebufferHeight, 1);
	int var8 = p_148259_4_.framebufferTextureHeight - p_148259_4_.framebufferHeight;

	for (int var9 = var8; var9 < p_148259_4_.framebufferTextureHeight; ++var9)
	{
		for (int var10 = 0; var10 < p_148259_4_.framebufferWidth; ++var10)
		{
			var7.setRGB(var10, var9 - var8, pixelValues[var9 * p_148259_4_.framebufferTextureWidth + var10]);
		}
	}
}
else
{
	var7 = new BufferedImage(p_148259_2_, p_148259_3_, 1);
	var7.setRGB(0, 0, p_148259_2_, p_148259_3_, pixelValues, 0, p_148259_2_);
}

File var12;

if (p_148259_1_ == null)
{
	var12 = getTimestampedPNGFileForDirectory(var5);
}
else
{
	var12 = new File(var5, p_148259_1_);
}

// Create an empty file to make sure a ScreenshotSavingThreads do not override it by accident
var12.createNewFile();

//ImageIO.write(var7, "png", var12);
class ScreenshotSavingThread extends Thread {
	private final BufferedImage bufferedImage;
	private final File file;
	
	private ScreenshotSavingThread(BufferedImage bufferedImage, File file) {
		this.bufferedImage = bufferedImage;
		this.file = file;
	}
	
	@Override
	public void run() {
		try {
			ImageIO.write(bufferedImage, "png", file);
		} catch (IOException e) {
			// TODO Print the error message in chat and in the log
		}
	}
}
new ScreenshotSavingThread(var7, var12).start();

Flaws with this design

Stopping Minecraft could cause half-finished screenshots (unlikely)
Taking screenshots to often results in a OutOfMemoryError (unlikely, that would need with 500KB per screenshot and 500MB allocated RAM about 1000 ScreenshotSavingThreads running at once)

Ezekiel 2016-01-03T18:29:08Z

Can confirm that even on my SSD the game still freezes up for a second

Noerdy 2016-02-29T01:33:38Z

This has been happening for ever, and there are definitely fixes, as there have been mods that fix this.

marcono1234 2016-02-29T09:21:01Z

Confirmed for

1.9-pre4

Ezekiel 2016-02-29T15:17:14Z

I just tested this again and the freeze was barely perceptible on the same hardware as I previously confirmed it on. I'm currently seeing a freeze of .24s (I used 60fps recording and video editing software to get the exact time).

Erik Broes 2016-12-06T11:28:45Z

Removed some unused ancient code 😞

slicedlime 2016-12-15T17:58:39Z

Is the fix version correct for this? It looks exactly the same in 16w50a to me.

Notex 2016-12-16T07:43:00Z

Still the same in 16w50a for me as well.

pokechu22 2018-07-29T23:02:28Z

Fixed in 18w30a; the image is now added to some kind of threaded executor for writing rather than being written on the main thread.

(The weird bufferedwriter pixel copying code is also gone, but I think that's what was removed in 16w50a).