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https://issues.apache.org/jira/browse/KNOX-864?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Attila Kanto updated KNOX-864:
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Status: Patch Available (was: Open)
Proposed solution is identical what has been implemented for Ambari Server.
There is no change in the default behaviour, but if the
GATEWAY_SERVER_RUN_IN_FOREGROUND or LDAP_SERVER_RUN_IN_FOREGROUND to true e.g
in Upstart conf files, then LDAP and Knox Gateway is started in foreground
which makes the tracking of right PID quite easy for Upstart.
> Knox init scripts are not Upstart compatible
> --------------------------------------------
>
> Key: KNOX-864
> URL: https://issues.apache.org/jira/browse/KNOX-864
> Project: Apache Knox
> Issue Type: Improvement
> Components: Server
> Affects Versions: 0.11.0
> Reporter: Attila Kanto
>
> It is critical that we have a service that can auto-restart during crashes
> and reboots. On Amazon Linux this tasks are done by Upstart.
> By default Upstart will track the life cycle of the first PID that it
> executes in the exec or script stanzas (defined in the Upstart config file),
> however, most Unix services will "daemonize", meaning that they will create a
> new process (using fork(2)) which is a child of the initial process. This is
> what also happens when when gateway.sh or ldap.sh is invoked.
> In order to track the right PID, Upstart must determine the final process ID
> for a job, and in case of daemonized processes it needs to know how many
> times that process will call fork(2).
> Upstart supports the followings:
> * *expect fork*: Upstart will expect the process executed to call fork(2)
> exactly once.
> * *expect daemon*: Upstart will expect the process executed to call fork(2)
> exactly twice
> Unfortunately none of the above cases fits to gateway.sh and ldap.sh, since
> they are calling fork many times and Upstart always tracks the wrong PID.
> According to Upstart doc
> http://upstart.ubuntu.com/cookbook/#how-to-establish-fork-count if the
> application you are attempting to create a Job Configuration File does not
> document how many times it forks, you can run it with a tool such as
> strace(1) which will allow you to count the number of forks:
> {code}
> [root@ip-10-0-4-107 ~]# strace -o /tmp/strace.log -fFv su -c
> "/usr/hdp/current/knox-server/bin/gateway.sh start" knox
> Starting Gateway succeeded with PID 25528.
> [root@ip-10-0-4-107 ~]# sudo egrep "\<(fork|clone)\>\(" /tmp/strace.log | wc
> | awk '{print $1}'
> 86
> {code}
> Ambari had similar issues in the past:
> https://issues.apache.org/jira/browse/AMBARI-14842
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