[
https://issues.apache.org/jira/browse/QPID-5637?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Brian Bouterse updated QPID-5637:
---------------------------------
Attachment: 0001-Fix-for-QPID-5637.patch
This patch makes the Selector object pid aware, and implements Selector to
provide the singleton pattern per pid instead of a singleton pattern for all
parent/child.
> qpid.messaging Issues With Forking
> ----------------------------------
>
> Key: QPID-5637
> URL: https://issues.apache.org/jira/browse/QPID-5637
> Project: Qpid
> Issue Type: Bug
> Components: Python Client
> Affects Versions: 0.24
> Reporter: Brian Bouterse
> Fix For: 0.18, 0.22, 0.24, 0.26, 0.27
>
> Attachments: 0001-Fix-for-QPID-5637.patch
>
>
> qpid.messaging has an issue with forking in the following situation.
> 1. A parent Python process imports and uses qpid.messaging to connect to a a
> Qpid broker
> 2. The parent process forks a child process
> 3. The child process imports qpid.messaging and tries to connect to a Qpid
> broker.
> I expected to see the child process use qpid.messaging normally as it would
> if it weren't forked in the way described above. Instead, the server
> receives the opening of a TCP socket, but the client never sends the AMQP
> protocol announcement.
> The root cause of this issue is in the file descriptors registered by the
> Selector object inside of qpid.messaging. The Selector object uses a
> singleton pattern to provide a reference to the same Selector object no
> matter how many times you call it. This selector object already has
> registered file descriptors with the filesystem, which allow the selector to
> read/write data in an I/O efficient manner.
> When forking occurs, the child process receives a copy of the Python running
> space (ie: the Selector singleton), but the kernel is not registered with
> file descriptors that are available in the child process' new file descriptor
> table. This breaks usage of qpid.messaging in the client process because
> when qpid.messaging relies on the epoll functionality of Selector, Selector
> does not fulfill that expectation.
> The solution is to have the class method that implements the singleton
> pattern on the Selector object to be process aware, and implement the
> singleton pattern per process.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@qpid.apache.org
For additional commands, e-mail: dev-h...@qpid.apache.org
