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https://issues.apache.org/jira/browse/ZOOKEEPER-770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13050289#comment-13050289
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Craig Calef commented on ZOOKEEPER-770:
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This bug was also causing me some problems. After digging into the C code it
occured to me that the problem was down through add_auth() to
send_info_packet(), which was putting the auth packet on the to_send queue but
not waking up the IO thread via adaptor_send_queue() like send_ping() does.
The result was the auth packet didn't go out until the zoo_interest() timeout
occured (which internally looks to be like 1/3rd the timeout specified in the
zookeeper_init, but I don't 100% grok what zoo_interest is doing) Attached is
a very simple patch which remedies this problem, and does not have any other
appreciable impact. For me it cut the time it took for the add_auth watch to
fire to practically instantaneous.
> Slow add_auth calls with multi-threaded client
> ----------------------------------------------
>
> 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
> Priority: Minor
> Attachments: ZOOKEEPER-770-FIX.patch, authtest.py
>
>
> 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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