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https://issues.apache.org/jira/browse/HBASE-29493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18012571#comment-18012571
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Umesh Kumar Kumawat commented on HBASE-29493:
---------------------------------------------
I don't know how can we check if particulat block is drained or not. A simple
sleep might not work in all the cases. I was thinking of calling
stopWriterThreads(). Here we have two options
# call stopWriterThreads() before caching the block, this way we will only
interact with ramCache only.
# Calling stopWriterThreads() after caching the block. While stoping all
writers we do wait for writers to complete their work, this way we can make
sure that block has moved to backing map.
> TestBucketCacheRefCnt.testInBucketCache fails if block found after eviction
> ---------------------------------------------------------------------------
>
> Key: HBASE-29493
> URL: https://issues.apache.org/jira/browse/HBASE-29493
> Project: HBase
> Issue Type: Bug
> Components: BucketCache
> Reporter: Umesh Kumar Kumawat
> Assignee: Umesh Kumar Kumawat
> Priority: Minor
>
> {code:java}
> HFileBlock blk = createBlock(200, 1020, alloc);
> BlockCacheKey key = createKey("testHFile-00", 200);
> cache.cacheBlock(key, blk);
> assertTrue(blk.refCnt() == 1 || blk.refCnt() == 2);
> Cacheable block1 = cache.getBlock(key, false, false, false);
> assertTrue(block1.refCnt() >= 2);
> assertTrue(((HFileBlock) block1).getByteBuffAllocator() == alloc);
> Cacheable block2 = cache.getBlock(key, false, false, false);
> assertTrue(((HFileBlock) block2).getByteBuffAllocator() == alloc);
> assertTrue(block2.refCnt() >= 3);
> cache.evictBlock(key);
> assertTrue(blk.refCnt() >= 1);
> assertTrue(block1.refCnt() >= 2);
> assertTrue(block2.refCnt() >= 2);
> // Get key again
> Cacheable block3 = cache.getBlock(key, false, false, false);
> if (block3 != null) {
> assertTrue(((HFileBlock) block3).getByteBuffAllocator() == alloc);
> assertTrue(block3.refCnt() >= 3);
> assertFalse(block3.release());
> }
> {code}
> In starting of the cache the block is stored in ramCache and later we drain
> it to backingMap async. This test work fine if we only interact with ramCache
> but sometime drain get completed just before we try to get the block again
> after eviction. Wheneve the block moves to backingMap it start the ref from
> fresh so either 1 or 2. And because of this Assertion in the if fails.
> Stack trace -
> {noformat}
> java.lang.AssertionError
> at org.junit.Assert.fail(Assert.java:87)
> at org.junit.Assert.assertTrue(Assert.java:42)
> at org.junit.Assert.assertTrue(Assert.java:53)
> at
> org.apache.hadoop.hbase.io.hfile.bucket.TestBucketCacheRefCnt.testInBucketCache(TestBucketCacheRefCnt.java:249)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:498)
> at
> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
> at
> org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
> at
> org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
> at
> org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
> at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
> at
> org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
> at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
> at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
> at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
> at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
> at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
> at
> org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:288)
> at
> org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:282)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at java.lang.Thread.run(Thread.java:750)
> {noformat}
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