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Reduce permgen use from Groovy scripts #7658

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dakrone opened this Issue Sep 9, 2014 · 1 comment

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commented Sep 9, 2014

Groovy scripts seem to be using more permgen than MVEL scripts do, especially when sent dynamically.

It would be nice if we reduce the amount of permgen used by these scripts, or make the permgen space recoverable in the event the script is not used.

@dakrone dakrone self-assigned this Sep 9, 2014

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commented Sep 23, 2014

This is because the GroovyClassLoader hangs on to every class ever created in its class cache. In benchmarks, I can only load ~500 scripts into a Java7 vm with default permgen settings before OOM/permgen. I can get a few thousand in with Java8.

#!/bin/bash
i=0
while \
curl -m 3 -X POST localhost:9200/_search\?size=0 -d @- <<EOT
{
  "query": {
    "function_score": {
      "query": { "match_all": {} },
      "script_score": {
        "script": "$(echo `date +%s`.$RANDOM)",
        "lang": "groovy"
      }
    }
  }
}
EOT
do 
  i=$((i+1))
  echo
done

echo failed after $i iterations

The following patch works for me for dynamic scripts, and I believe it shouldn't have a downside, because (1) ES has it's own Guava class cache (that actually releases classes), and (2) I can't find a codepath in ES that even indirectly uses the GroovyClassLoader's class cache.

# GroovyScriptEngineService.java#113
+ loader.clearCache();
return loader.parseClass(script, generateScriptName());

dakrone added a commit to dakrone/elasticsearch that referenced this issue Oct 14, 2014

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes elastic#7658

dakrone added a commit that referenced this issue Oct 14, 2014

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes #7658

dakrone added a commit that referenced this issue Oct 14, 2014

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes #7658

dakrone added a commit that referenced this issue Oct 14, 2014

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes #7658

mute pushed a commit to mute/elasticsearch that referenced this issue Jul 29, 2015

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes elastic#7658

mute pushed a commit to mute/elasticsearch that referenced this issue Jul 29, 2015

Clear the GroovyClassLoader cache before compiling
Since we don't use the cache, it's okay to clear it entirely if needed,
Elasticsearch maintains its own cache for compiled scripts.

Adds loader.clearCache() into a listener, the listener is called when a
script is removed from the Guava cache.

This also lowers the amount of cached scripts to 100, since 500 is
around the limit some users have run into before hitting an out of
memory error in permgem.

Fixes elastic#7658
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