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https://issues.apache.org/jira/browse/HBASE-7205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13529614#comment-13529614
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Ted Yu commented on HBASE-7205:
-------------------------------
Did some experiment. First, as
http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/management/ManagementFactory.html#getGarbageCollectorMXBeans%28%29
says, we may need to deal with several GarbageCollectorMXBean's.
Here is what I came up with:
{code}
admin.disableTable(htd.getName());
admin.deleteTable(htd.getName());
List<GarbageCollectorMXBean> mxbeans =
ManagementFactory.getGarbageCollectorMXBeans();
LOG.info("There are " + mxbeans.size() + " MXBeans");
GarbageCollectorMXBean mxbean = mxbeans.get(0);
long initialCollectionCount = mxbean.getCollectionCount();
long startTime = System.currentTimeMillis();
System.gc();
while (mxbean.getCollectionCount() == initialCollectionCount &&
System.currentTimeMillis() - startTime < 30000) {
Thread.sleep(10);
}
for (Path p : CoprocessorHost.classLoadersCache.keySet()) {
ClassLoader cl = CoprocessorHost.classLoadersCache.get(p);
assertTrue(" " + cl, cl == null);
}
{code}
After waiting for 30 seconds, the assertion fails:
{code}
testClassLoadingFromHDFS(org.apache.hadoop.hbase.coprocessor.TestClassLoading)
Time elapsed: 39.79 sec <<< FAILURE!
java.lang.AssertionError:
org.apache.hadoop.hbase.coprocessor.CoprocessorClassLoader@24e7cb66
at org.junit.Assert.fail(Assert.java:93)
at org.junit.Assert.assertTrue(Assert.java:43)
at
org.apache.hadoop.hbase.coprocessor.TestClassLoading.testClassLoadingFromHDFS(TestClassLoading.java:339)
{code}
I don't know how long the test should wait for GC to kick in.
> Coprocessor classloader is replicated for all regions in the HRegionServer
> --------------------------------------------------------------------------
>
> Key: HBASE-7205
> URL: https://issues.apache.org/jira/browse/HBASE-7205
> Project: HBase
> Issue Type: Bug
> Components: Coprocessors
> Affects Versions: 0.92.2, 0.94.2
> Reporter: Adrian Muraru
> Assignee: Ted Yu
> Priority: Critical
> Fix For: 0.96.0, 0.94.4
>
> Attachments: 7205-0.94.txt, 7205-v10.txt, 7205-v1.txt, 7205-v3.txt,
> 7205-v4.txt, 7205-v5.txt, 7205-v6.txt, 7205-v7.txt, 7205-v8.txt, 7205-v9.txt,
> HBASE-7205_v2.patch
>
>
> HBASE-6308 introduced a new custom CoprocessorClassLoader to load the
> coprocessor classes and a new instance of this CL is created for each single
> HRegion opened. This leads to OOME-PermGen when the number of regions go
> above hundres / region server.
> Having the table coprocessor jailed in a separate classloader is good however
> we should create only one for all regions of a table in each HRS.
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