polarbear316

It indeed has improved, only being halved now from ~122fps to ~60fps, so quite more playable than before.

Yes issue still persists in 1.13.1 although slight improvement from the snapshots. Takes a slightly higher column, 11 high in my case, to get the frames to go all the way down to around 1-10.

Still is directional, only occurring when facing east. 

Isn't an issue if particles are set to minimal, or when using any other block other than a powered piston

Try with seed: 3642435227587432100

and portal at coordinates: -8659, 25, 12084

This is the one that the game never recovered for me with.

Also forgot to look in the logs last time, cleared all the old logs and tried again. It seems during this desynced time there is a continuous IndexOutOfBoundsException which only starts at the time of desync (full log:

):

java.util.concurrent.ExecutionException: java.lang.IndexOutOfBoundsException: bitIndex < 0: -33353016
	at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_51]
	at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_51]
	at k.a(SourceFile:199) [1.13.jar:?]
	at net.minecraft.server.MinecraftServer.w(SourceFile:701) [1.13.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:656) [1.13.jar:?]
	at dfx.v(SourceFile:157) [1.13.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:559) [1.13.jar:?]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51]
Caused by: java.lang.IndexOutOfBoundsException: bitIndex < 0: -33353016
	at java.util.BitSet.get(BitSet.java:623) ~[?:1.8.0_51]
	at cdw.a(SourceFile:71) ~[1.13.jar:?]
	at axw.a(SourceFile:193) ~[1.13.jar:?]
	at axw.a(SourceFile:258) ~[1.13.jar:?]
	at axw.a(SourceFile:242) ~[1.13.jar:?]
	at axw.a(SourceFile:226) ~[1.13.jar:?]
	at aeo.a(SourceFile:639) ~[1.13.jar:?]
	at ub.a(SourceFile:772) ~[1.13.jar:?]
	at mu.a(SourceFile:126) ~[1.13.jar:?]
	at mu$b.a(SourceFile:18) ~[1.13.jar:?]
	at ix.a(SourceFile:10) ~[1.13.jar:?]
	at ix$$Lambda$1679/2114959646.run(Unknown Source) ~[?:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_51]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_51]
	at k.a(SourceFile:198) ~[1.13.jar:?]
	... 5 more

Can confirm. Seems to be direction based. As when testing various portals, portal rooms facing north (doorway, spawner, portal frame in north direction) and west (again doorway, spawner, portal frame in west direction) seemed to cause the issue. Issue didn't occur for east facing portal rooms, couldn't find a south facing one to test.

The amount of time for the internal server to "resync" varies. One portal room took a couple minutes, others never resynced.

Reproduceable by:

1. Create new world

2. Find stronghold with north or west facing portal room

3. Set a bed spawn, at / near portal

4. Go through end portal

5. Kill dragon if haven't already (issue exists even if you try this after having killed dragon previously)

6. Go through end portal to overworld.

7. You will be desynced, can't access chests, placing a bed will only place the foot(head won't generate), blocks aren't dropped, etc. Looking at debug screen while it lists packets being sent (tx of 1 or more), it shows no received packets (rx of 0)

8. Wait a couple minutes and it might resync. If you save and close before resync you will rejoin at the point of the last autosave

Note tested on Windows 10, java 1.8.0_171-b11