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From "Matt Magoffin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FELIX-5383) Support parallel bundle starting
Date Mon, 17 Oct 2016 18:37:59 GMT

    [ https://issues.apache.org/jira/browse/FELIX-5383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15583051#comment-15583051
] 

Matt Magoffin commented on FELIX-5383:
--------------------------------------

Here's a fork of the 3.5.4 release of File Install where I implemented this concept:

https://github.com/msqr/felix/blob/fileinstall-start-async

The [changes are in DirectoryWatcher.java|https://github.com/msqr/felix/commit/5769cdc57060026b9f3e62ddc9f1cb6144bb4a19],
mostly [centered around|https://github.com/msqr/felix/blob/5769cdc57060026b9f3e62ddc9f1cb6144bb4a19/src/main/java/org/apache/felix/fileinstall/internal/DirectoryWatcher.java#L1245]
the {{startBundles(Collection<Bundle> bundles)}} method.

The changes introduce two configurable properties:

1.  {{felix.fileinstall.start.tasks}} for the maximum number or parallel start tasks to execute,
or if >= 99 than unlimited.
2. {{felix.fileinstall.start.tasksRetryDelay}} for a number of seconds to delay before re-trying
to start bundles that failed to do so.

The {{tasksRetryDelay}} property was needed because if, like in my case, the {{poll}} time
is set to {{0}} then there needs to be a way to retry starting failed bundles.

This was my first time looking at the File Install code, so I'm not confident the changes
are completely appropriate, but hopefully the idea of parallel starting is useful to others
more generally.

> Support parallel bundle starting
> --------------------------------
>
>                 Key: FELIX-5383
>                 URL: https://issues.apache.org/jira/browse/FELIX-5383
>             Project: Felix
>          Issue Type: Improvement
>          Components: File Install
>    Affects Versions: fileinstall-3.5.4
>            Reporter: Matt Magoffin
>
> I have an application that uses Felix File Install to start a set of bundles that use
Blueprint configuration extensively, but with the poll time disabled ({{felix.fileinstall.poll
= 0}}) because I only want the bundles started at application startup time. Sometimes one
bundle might have a Blueprint service dependency provided by another bundle such that when
started and that other bundle has not been started yet causes a service timeout. The ordering
File Install uses to start bundles is indeterminate (a {{HashSet}} is passed to {{startBundles(Collection<Bundle>
bundles)}}) so I thought a good solution would be to start bundles in parallel, so if one
bundle gets stuck when starting, waiting for a Blueprint service to become available, other
bundles can continue to be started under the assumption one of them will be providing that
service "soon".



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