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From Ke Ren ...@spaceapegames.com>
Subject HttpClient IO hits the same core
Date Mon, 14 Oct 2013 21:22:33 GMT

We are sending massive http client requests on amazon ec2 instance with 8
cores (m3.xlarge). We notice always one core is hammered the most (80%) but
others are just used around 30% to 40%. The httpclient we are using is
4.2.5. I reproduced this issue with very simple code on ec2 4 core
instance. Basically I created one http client instance new
DefaultHttpClient(mgr, params); mgr is a PoolingClientConnectionManager.
This http client instance is shared by multiple threads. In this test, each
thread worker just gets the same 700k file from s3. The result is the same.
always just one core is hit heavily but very low usage on others. From
jprofiler profiling, it looks the most cpu usage is on IO read from
InputStream. I used EntityUtils.toByteArray to read data from entity. From
netstat, there are 50 connections. The thing confuses me is why it always
hits the same core when http responses are processed from multiple threads.
Any ideas?

Thanks in advance,


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