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https://issues.apache.org/jira/browse/CASSANDRA-4338?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yuki Morishita updated CASSANDRA-4338:
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Attachment: 4338-gc.tar.gz
LCS with sstable_size_in_mb set to 1, I ran stress test again (n=20,000,000)
and get the gc log for both patched and trunk(logs attached).
GC log setting is below:
{code}
# GC logging options -- uncomment to enable
JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
{code}
So far, both logs show no indication of promotion failure.
bq. we might need to look at using our "cleaner" hack to free the direct
buffers, or use a buffer based on FreeableMemory, to avoid the phantomreference
crap that DirectBuffer normally inflicts on GC
My current implementation does not free Direct ByteBuffer. Since it costs some
time to allocate direct BB, it allocates large buffer at start up, slice it to
certain block size, and pool them to reuse. So I don't think switching to
FreeableMemory or Unsafe contribute improvement here.
I will start looking at the reading side (RAR/CRAR) and see what we can do
there.
> Experiment with direct buffer in SequentialWriter
> -------------------------------------------------
>
> Key: CASSANDRA-4338
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4338
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Yuki Morishita
> Priority: Minor
> Fix For: 1.2
>
> Attachments: 4338-gc.tar.gz, gc-4338-patched.png, gc-trunk.png
>
>
> Using a direct buffer instead of a heap-based byte[] should let us avoid a
> copy into native memory when we flush the buffer.
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