Game hangs while trying to load chunks

Appears to be happening on servers as well.

This issue has become very troublesome for me since the 18w50a build.  I cannot travel on foot across a map.  The next chunk loads very slowly or not at all.  This forces me to restart to get the chunk to load.  Teleporting hangs the game.  worldspawn even loads very slowly.  My system is capable, I7-8700k, 16G, gtx1070, and runs the release version with ease. My jvm arguments are default.  I've run d64 and bundled javaw with no difference.

I think I am affected as well

I do not experience this:

> world completely freezes 
but still, chunks do not load. I have to log out and reconnect to server to force chunks to load
Somehow that happens only with linux-running client, the one with windows loads chunks properly

I have the same issue as well, and...

Sometimes my game even crashes!

This should be a complete list of all things that dupe: Chunk Format Entities and Block Entities

Reproduction world attached - log in to coordinates t (491, 99, 523) to trigger the freeze.

Its due to a deadlock in the duplicate entity handling code.

How/why the entities duplicate is another bug, but in this case it appears to be duplicated cod/salmon.

Appears that my comment is incorrect - its only one of several ways in which this can occur.

The freeze as per the title is also occurring randomly during normal chunk loads from various places, but I do not yet know why.

Attached a crash report from 19w05a.

Can confirm in 19w06a

I confirm in 19w08a

This only occurs for me on a multiplayer server(19w09a) if the render distance in the client is set below the view distance configured in the server.properties file. Then the server wont load any more chunks outside the already loaded world.

I can confirm Kilian's findings

In my server.properties file is the view_distance set to 10. If I join the server with a client view distance of 10 or lower the bug occurs, but if I join with view distance 11 or higher I have no problems with this bug.

From my experience (not much) 9 has hanged but 8 works. Haven't tried much lower/higher than that.

I can also confirm Kilian's comment. The client's view distance must be higher than the server's.

Having a view_distance of 16 on the server, the client kept having a lot of problems loading chunks (with a view distance of 16). Changing the view distance to 17 and relogging completely solved the issue.

Very curious behavior. If you are reading this because you have this problem, this is a very good fix.

I have managed to fix my problem (the server would crash each time I left the end due to chunks not generating/loading at all) using the suggestion I found in this issue https://bugs.mojang.com/browse/MC-138114

In short, I set my client's view distance to be the same as the server's (10 chunks) and restarted both the server and my client. After that, no more crashes occurred and everything loaded flawlessly.

I think my problem was somehow specifically related to the credits screen, because after I got through that screen once, my client's render distance didn't matter anymore and I could set it to anything. Hopefully this could help someone in the future!

My issue in https://bugs.mojang.com/browse/MC-145300 has been added as part of this, however my world is exclusively single player and my render distance has already been maxed out. Tried changing the render distance but it had no effect on the world loading or changing after the world had loaded.

I am in 19w09a and had actually played quite a bit in the snapshot with no issue until logging off, then came back to find that the world refused to load properly and froze the game when attempting to leave.

still seems to be happening on my server though... will do some testing.
Edit: Still happening on my server with specific view distances.

Reopening as I'm still seeing this in 11b.

Stack is the same as before just with

sun.misc.Unsafe.park(Native Method)
java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)

At the top instead of yield.

Teleporting between worlds is the most reliable way to reproduce it (still not very reliable), but it definitely also happens just during the course of having a server played on for hours. Simply flying in a straight line even for extended periods of time does not reproduce it.

Another issue with method sun.misc.Unsafe.park() happening when kicking / banning any player from the server (outside the console). [MC-145994]

confirmed for 19w12a

now effecting 19w13a and the hang can be seen only in a server setting single player and open world single player words are uneffected

affected on single player in 19w13a

Currently happening on 19w13a multiplayer server.

When player quickly disconnects/reconnects, it properly loads all chunks nearby.

Confirmed for 19w13b