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Posted to issues@mesos.apache.org by "Kevin Klues (JIRA)" <ji...@apache.org> on 2017/01/07 01:44:58 UTC
[jira] [Updated] (MESOS-6879) IOSwitchboard should wait for stdin
to be closed and drained before exiting
[ https://issues.apache.org/jira/browse/MESOS-6879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Kevin Klues updated MESOS-6879:
-------------------------------
Description:
Currently, the IOSwitchboard assumes that whenever a container's {{stdout}} and {{stderr}} have been closed, then it is OK to exit the switchboard process. We assume this because {{stdout}} and {{stderr}} will only be closed after both the read end of the {{stdout}} stream and the read end of the {{stderr}} stream have been drained. Since draining these {{fds}} represents having read everything possible from a container's {{stdout}} and {{stderr}} this is likely sufficient termination criteria. However, there's a non-zero chance that *some* containers may decide to close their {{stdout}} and {{stderr}} while expecting to continue reading from {{stdin}}. For now we don't support containers with this behavior and we will exit out of the switchboard process early.
The reason we don't support this currently is that {{libevent}} and {{libev} don't provide a nice way of asynchronously detecting when an {{fd}} has been closed. If they did, we could easily leverage this to asynchronously wait until {{stdin}} was closed before killing the IOSwitchboard process.
Once these libraries support this (or we find a workaround) we should update the IOSwitchboard appropriately.
was:[~klueska] can you fill the description for this?
> IOSwitchboard should wait for stdin to be closed and drained before exiting
> ---------------------------------------------------------------------------
>
> Key: MESOS-6879
> URL: https://issues.apache.org/jira/browse/MESOS-6879
> Project: Mesos
> Issue Type: Improvement
> Reporter: Vinod Kone
> Assignee: Kevin Klues
>
> Currently, the IOSwitchboard assumes that whenever a container's {{stdout}} and {{stderr}} have been closed, then it is OK to exit the switchboard process. We assume this because {{stdout}} and {{stderr}} will only be closed after both the read end of the {{stdout}} stream and the read end of the {{stderr}} stream have been drained. Since draining these {{fds}} represents having read everything possible from a container's {{stdout}} and {{stderr}} this is likely sufficient termination criteria. However, there's a non-zero chance that *some* containers may decide to close their {{stdout}} and {{stderr}} while expecting to continue reading from {{stdin}}. For now we don't support containers with this behavior and we will exit out of the switchboard process early.
> The reason we don't support this currently is that {{libevent}} and {{libev} don't provide a nice way of asynchronously detecting when an {{fd}} has been closed. If they did, we could easily leverage this to asynchronously wait until {{stdin}} was closed before killing the IOSwitchboard process.
> Once these libraries support this (or we find a workaround) we should update the IOSwitchboard appropriately.
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