Jonathan Hurley created AMBARI-14050:
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Summary: Produce a Warning When Jetty Pool Size Is Too Low And
Increase It
Key: AMBARI-14050
URL: https://issues.apache.org/jira/browse/AMBARI-14050
Project: Ambari
Issue Type: Bug
Components: ambari-server
Affects Versions: 2.0.0
Reporter: Jonathan Hurley
Assignee: Jonathan Hurley
Priority: Critical
Fix For: 2.1.3
Ambari's default Jetty thread pool is configured at 25 threads. When deployed
on a machine that has 48 "processors", Jetty's calculation for determining how
many "Acceptor" and "Selector" threads to create never takes into account the
core pool size. As a result, we get:
- 12 "Acceptor" threads (these answer binds to port 8080)
- 12 "Selector" threads (these pick available threads to answer bindings)
- 1 free thread (these are the threads available to do stuff with)
Notice that there's only 1 free thread. This means that Jetty effectively makes
Ambari a single-threaded web application on larger systems!
The "fix" is to increase the thread count in the {{ambari.properties}}, however
nobody knows to do this since no warning is produced.
I suggest:
- Log a warning on server startup if we detect that the core pool size is less
than 3/4 of the available processors on the system.
- Automatically increase the core pool size to the min(100, double existing
size) when the above is detected
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