[GitHub] merlimat commented on issue #1321: Avoid contention on netty channel promise

[GitBox <gi...@apache.org>]

merlimat commented on issue #1321: Avoid contention on netty channel promise
URL: https://github.com/apache/bookkeeper/pull/1321#issuecomment-379320906
 
 
   > what is the impact of this change? like how much performance change we can get? do you have a microbenchmark for that?
   
   I cannot quantify directly the impact yet. I'm working to remove other contention points in Pulsar code. The results are only visible when most contention points are removed. 
   
   | Monitor Class                           |	Total Blocked Time |	Maximum Blocked Time  |	Average Blocked Time    |	Std Dev Blocked Time | 	Distinct Threads	| Count | Distinct Addresses |
   | -------------                           | -------------      | -------------          | -------------           | -------------        | -------------     | ----- | -------------        |
   | io.netty.channel.DefaultChannelPromise	| 7.53794229E8 ns	   | 41358171 ns	          |1.6750982866666667E7 ns	|6124170.655041036 ns  | 15	              | 45    |	45                   |
   
   
   Basically this means that this mutex has blocked IO threads for a total of 753 millis (the profiling was done over 5minutes at 100K writes/s). That is all added to latency.
   
   
   ```
   void io.netty.util.concurrent.DefaultPromise.checkNotifyWaiters()	45
   boolean io.netty.util.concurrent.DefaultPromise.setValue0(Object)	45
   boolean io.netty.util.concurrent.DefaultPromise.setSuccess0(Object)	45
   boolean io.netty.util.concurrent.DefaultPromise.trySuccess(Object)	45
   void io.netty.util.internal.PromiseNotificationUtil.trySuccess(Promise, Object, InternalLogger)	45
   void io.netty.channel.ChannelOutboundBuffer.safeSuccess(ChannelPromise)	45
   boolean io.netty.channel.ChannelOutboundBuffer.remove()	45
   void io.netty.channel.ChannelOutboundBuffer.removeBytes(long)	45
   int io.netty.channel.epoll.AbstractEpollStreamChannel.writeBytesMultiple(ChannelOutboundBuffer, IovArray)	45
   int io.netty.channel.epoll.AbstractEpollStreamChannel.doWriteMultiple(ChannelOutboundBuffer)	45
   void io.netty.channel.epoll.AbstractEpollStreamChannel.doWrite(ChannelOutboundBuffer)	45
   void io.netty.channel.AbstractChannel$AbstractUnsafe.flush0()	45
   void io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.flush0()	45
   void io.netty.channel.AbstractChannel$AbstractUnsafe.flush()	45
   void io.netty.channel.DefaultChannelPipeline$HeadContext.flush(ChannelHandlerContext)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush0()	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush()	45
   ChannelHandlerContext io.netty.channel.AbstractChannelHandlerContext.flush()	45
   void io.netty.channel.ChannelOutboundHandlerAdapter.flush(ChannelHandlerContext)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush0()	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush()	45
   ChannelHandlerContext io.netty.channel.AbstractChannelHandlerContext.flush()	45
   void io.netty.channel.ChannelOutboundHandlerAdapter.flush(ChannelHandlerContext)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush0()	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush()	45
   ChannelHandlerContext io.netty.channel.AbstractChannelHandlerContext.flush()	45
   void io.netty.channel.ChannelOutboundHandlerAdapter.flush(ChannelHandlerContext)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush0()	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeFlush()	45
   ChannelHandlerContext io.netty.channel.AbstractChannelHandlerContext.flush()	45
   void io.netty.channel.ChannelDuplexHandler.flush(ChannelHandlerContext)	45
   void org.apache.bookkeeper.proto.AuthHandler$ClientSideHandler.write(ChannelHandlerContext, Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext.invokeWrite(Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext.access$1900(AbstractChannelHandlerContext, Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext, Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext, Object, ChannelPromise)	45
   void io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run()	45
   void io.netty.util.concurrent.AbstractEventExecutor.safeExecute(Runnable)	45
   boolean io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(long)	45
   void io.netty.channel.epoll.EpollEventLoop.run()	45
   void io.netty.util.concurrent.SingleThreadEventExecutor$5.run()	45
   void io.netty.util.concurrent.FastThreadLocalRunnable.run()	45
   void java.lang.Thread.run()	45
   ```
   

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