ThreadDeath problem

Searching on my system and old backups I was able to find Robocode versions for 1.7.4.2, 1.8.1.0. I was also able to download 1.8.0.0 and 1.9.0.0. So I ran some experiments using Neuromaner vs RaikoMicro. Note, dev version of Neuromancer I'm using here prints out each time it gets a SkippedTurnEvent.

• I can't reproduce it in at all 1.7.4.2. All output looks perfect - every round has printed SYSTEM lines either saying win or death, and Neuromancer correctly gets win/death events. Neuromancer doesn't skip any turns.

• I can't reproduce it at all in 1.8.0.0 - not even "SYSTEM: Neuromancer 5.4 has not performed any actions in a reasonable amount of time." However there are some rounds where nothing is printed, which is very suspicious. Still no skipped turn events.

• In 1.8.1.0 I can sometimes get a "SYSTEM: Neuromancer 5.4 has not performed any actions in a reasonable amount of time.". I saw this 3 times out of 10+ battles. There are also the occasional suspicious blank rounds where Neuromancer prints nothing, and SYSTEM prints nothing. Still no skipped turn events.

• In 1.9.0.0 I can reproduce ThreadDeath exceptions. On average 1 per battle, but sometimes 0 and max I saw was 4. Average of 3 skipped turn events per battle.

To note: all of them had similar CPU constants (between 5.3ms and 5.4ms).

Other things I tried:

• Changing the GC algorithm doesn't affect the number of ThreadDeaths in 1.9.0.0

• Doing a single getDataDirectory() at the beginning of each round doesn't affect the number of ThreadDeaths in 1.9.0.0

This makes me think it is a Robocode bug - possibly multiple bugs, since we have very different behaviors here over the different versions. It also greatly worries me that bots which were fine in 1.7.4.2 have problems in new versions.

Hi Skilgannon,

Isolating robocode issues from jdk version. Would it be correct to assume that you ran everything with openjdk-8?

Yes, all OpenJDK 8

openjdk version "1.8.0_131"
OpenJDK Runtime Environment (build 1.8.0_131-8u131-b11-2ubuntu1.16.04.3-b11)
OpenJDK 64-Bit Server VM (build 25.131-b11, mixed mode)