Slow add_auth calls with multi-threaded client
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Key: ZOOKEEPER-770
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-770
Project: Zookeeper
Issue Type: Bug
Components: c client, contrib-bindings
Affects Versions: 3.3.0, 3.4.0
Environment: ubuntu lucid (10.04), zk trunk (3.4)
Reporter: Kapil Thangavelu
Calls to add_auth are a bit slow from the c client library. The auth callback
typically takes multiple seconds to fire. I instrumented the java, c binding,
and python binding with a few log statements to find out where the slowness was
occuring (
http://bazaar.launchpad.net/~hazmat/zookeeper/fast-auth-instrumented/revision/647).
It looks like when the io thread polls, it doesn't register interest in the
incoming packet, so the auth success message from the server and the auth
callback are only processed when the poll timeouts. I tried modifying
mt_adapter.c so the poll registers interest in both events, this causes a
considerably more wakeups but it does address the issue of making add_auth
fast. I think the ideal solution would be some sort of additional auth
handshake state on the handle, that zookeeper_interest could utilize to suggest
both POLLIN|POLLOUT are wanted for subsequent calls to poll during the auth
handshake handle state.
i'm attaching a script that takes 13s or 1.6s for the auth callback depending
on the session time out value (which in turn figures into the calculation of
the poll timeout).
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