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https://issues.apache.org/jira/browse/ACCUMULO-4153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15165540#comment-15165540
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ASF GitHub Bot commented on ACCUMULO-4153:
------------------------------------------
Github user brianloss commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/73#discussion_r54019025
--- Diff:
core/src/main/java/org/apache/accumulo/core/file/rfile/bcfile/Compression.java
---
@@ -147,25 +148,27 @@ public synchronized OutputStream
createCompressionStream(OutputStream downStream
},
GZ(COMPRESSION_GZ) {
- private transient DefaultCodec codec;
+ private transient AtomicReference<DefaultCodec> codec = new
AtomicReference<DefaultCodec>();
@Override
- synchronized CompressionCodec getCodec() {
- if (codec == null) {
- codec = new DefaultCodec();
- codec.setConf(conf);
+ CompressionCodec getCodec() {
+ DefaultCodec resultCodec = codec.get();
+ if (null == resultCodec) {
+ DefaultCodec newCodec = new DefaultCodec();
--- End diff --
If a bunch of threads all got to this point at the same time, they would
all create a new DefaultCodec. Only one will succeed on the compareAndSet
below, but the code is still potentially creating many DefaultCodec instances
which will get garbage collected.
Since isSupported returns true, I'm wondering if it's possible to simply
initialize the member variable at construction time, and then the
AtomicReference wouldn't be needed either? But maybe I'm missing something
obvious.
> Change getCodec method in BCFile's Compression class
> ----------------------------------------------------
>
> Key: ACCUMULO-4153
> URL: https://issues.apache.org/jira/browse/ACCUMULO-4153
> Project: Accumulo
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.6.5
> Reporter: marco polo
> Assignee: marco polo
> Priority: Minor
> Fix For: 1.6.6, 1.7.2, 1.8.0
>
> Attachments: patchCompression
>
>
> Seeing major blockages blockages on the Synchronized method of getCodec. My
> initial change was to change it to double checked locking; however, spoke
> with [~kturner] and I'm changing this to an AtomicReference. Have a patch for
> the former but am in the process of testing the AtomicReference patch
> Note this is for Gzip
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