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https://issues.apache.org/jira/browse/QPID-2367?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12828278#action_12828278
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Jason Schlauch commented on QPID-2367:
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Yes, you don't need to handle anything other than stdout, stdin, and stderr.
However, for whatever reason, boilerplate daemon code often suggests (and goes
on to implement) closing all file descriptors. So perhaps "best practice"
wasn't quite accurate, and "common practice" or "it was in the code you
inherited" might be better.
I handled this by simply changing the daemon code to close only stdout, stdin,
and stderr. Finding the error, however, took up a fair chunk of time. Some
defensive coding in the QPID client might save others the same trouble.
For example, could you simply check if the fd was open before attempting to use
it (and reopen it if it's not)?
> Early Initialization of File Descriptors Conflicts With Daemon Best Practices
> -----------------------------------------------------------------------------
>
> Key: QPID-2367
> URL: https://issues.apache.org/jira/browse/QPID-2367
> Project: Qpid
> Issue Type: Improvement
> Components: C++ Client
> Affects Versions: 0.5
> Environment: Linux (possibly all UNIX), c++, g++
> Reporter: Jason Schlauch
>
> At least one file descriptor (in qpid/sys/epoll/EpollPoller.*) in the c++
> client is global and declared as static. In programs linked against the c++
> qpid libs g++ generates code for allocation and, more importantly,
> initialization of these descriptors that occurs before main(). You can
> confirm this with gdb by breakpointing both the initialization and main()
> (the initialization break is hit first).
> On the other hand, the canonical recipe for creating a UNIX daemon calls for
> the closing of all open file descriptors after fork()ing (where the fork()
> certainly occurs after main()). While not an absolute requirement, closing
> all open file descriptors is considered a best practice. A loop to close all
> descriptors is also common in boilerplate daemon creation code and has
> undoubtedly been cut-and-pasted into numerous daemons.
> The net effect is that the typical daemon will close the file descriptor
> opened before main() in the c++ client library. In the case of the epoll
> code this manifests as an inability to connect to the broker.
> A fix for this would be to defer the initialization of the file descriptor
> (perhaps via the Singleton pattern or a move of the variables into a class
> member).
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