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https://issues.apache.org/jira/browse/HADOOP-18534?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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xinqiu.hu updated HADOOP-18534:
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> Propose a mechanism to free the direct memory occupied by RPC Connections
> -------------------------------------------------------------------------
>
> Key: HADOOP-18534
> URL: https://issues.apache.org/jira/browse/HADOOP-18534
> Project: Hadoop Common
> Issue Type: Improvement
> Components: rpc-server
> Reporter: xinqiu.hu
> Priority: Minor
>
> In the RPC Client, a thread called RpcRequestSender is responsible for
> writing the connection request to the socket. Every time a request is sent, a
> direct memory is applied for in sun.nio.ch.IOUtil#write() and cached.
> If Connection and RpcRequestSender are promoted to the old generation, they
> will not be recycled when full gc is not performed, resulting in the
> DirectByteBuffer cached in sun.nio.ch.Util not being recycled. When the
> memory occupied by DirectByteBuffer is too large, the jvm process may not
> have the opportunity to do full gc and is killed.
> Unfortunately, there is no easy way to free these DirectByteBuffers.
> Perhaps, we can manually free these DirectByteBuffers by the following
> methods when the Connection is closed.
> {code:java}
> private void freeDirectBuffer() {
> try {
> ByteBuffer buffer = Util.getTemporaryDirectBuffer(1);
> int i = 0;
> while (buffer.capacity() != 1 && i < 1024) {
> ((DirectBuffer) buffer).cleaner().clean();
> buffer = Util.getTemporaryDirectBuffer(1);
> i++;
> }
> ((DirectBuffer) buffer).cleaner().clean();
> } catch (Throwable t) {
> LOG.error("free direct memory error, connectionId: " + remoteId, t);
> }
> }{code}
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