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From "Arjen van der Meijden (JIRA)" <j...@apache.org>
Subject [jira] Created: (AMQ-1739) ActiveMQ 5.1.0 runs out of file descriptors with lots of 'CLOSE_WAIT' sockets
Date Wed, 21 May 2008 11:00:54 GMT
ActiveMQ 5.1.0 runs out of file descriptors with lots of 'CLOSE_WAIT' sockets
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                 Key: AMQ-1739
                 URL: https://issues.apache.org/activemq/browse/AMQ-1739
             Project: ActiveMQ
          Issue Type: Bug
          Components: Broker
    Affects Versions: 5.1.0
         Environment: We have a single broker with no special network-stuff. Our broker-system
has two single core Opterons, 8GB of memory, plenty of I/O and runs a recent 64bit debian
with 2.6.21 kernel.

Java(TM) SE Runtime Environment (build 1.6.0_06-b02)
Java HotSpot(TM) 64-Bit Server VM (build 10.0-b22, mixed mode)

We left most of the activemq.xml-configuration as-is and adjusted the start-up script to run
with 2GB heap size and parallel garbage collector, which was more or less needed for 5.0 and
left for 5.1 in the start-up script.
            Reporter: Arjen van der Meijden
            Priority: Blocker


We have no idea why or when, but within a few days after start-up, ActiveMQ suddenly runs
out of file descriptors (we've raised the limit to 10240). According to lsof it has lots of
sockets which are in CLOSE_WAIT when that happens. As soon as that happened once, it would
re-occur within a few hours. This behavior did not happen with ActiveMQ 5.0.

We have five queues, all with only one consumer. All consumption and production is via the
Stomp-interface using PHP-clients. Three of those queues get up to 50-100 messages/second
in peak moments, while the consumers adjust their own consumption rate to the systems load
(normally its maxed to about 50-150/sec). So in high-load moments on the consumers, the queues
can grow to a few thousand messages, normally the queues are emptied as soon as a message
occurs. Those five consumers stay connected indefinitely.

The messages are all quite small (at most 1 KB or so) and come from 5 web servers. For each
web page-request (about 2-3M/day) a connection is made to ActiveMQ via Stomp and at least
one message is sent to ActiveMQ, for most requests two are sent to the two most active queues.
For all request a new connection is made and at most 4 stomp-messages are sent to ActiveMQ
(connect, two messages, disconnect), since apache+php does not allow useful reuse of sockets
and similar resources.So 
So the connection-rate is about the same as the highest message rate on any of the queues
(so 50-100connects/second).

When the high amount of sockets in CLOSE_WAIT occurs, we manually disable the producers and
the sockets disappear gradually. After that the amount of sockets stays around 180-190 (mostly
opened jars), but seams to re-increase more easily than when ActiveMQ is restarted. I have
not checked if anything special happens on the web servers or databases, since their producer
and consumer implementation has not changed since 5.0.

What I did notice is that the memory-consumption increases heavily prior to running out of
descriptors, and the consumption re-increases way to fast compared to before 11:45u:
http://achelois.tweakers.net/~acm/tnet/activemq-5.1-memory-consumption.png

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