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[Xen-API] [RFC][PATCH] Deadlock in RRD handling during master transition

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Subject: [Xen-API] [RFC][PATCH] Deadlock in RRD handling during master transition
From: "Ted Lin" <tlin@xxxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 9 Aug 2010 11:52:02 -0400
Delivery-date: Mon, 09 Aug 2010 09:25:18 -0700
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Thread-topic: [RFC][PATCH] Deadlock in RRD handling during master transition
The codebase that this XAPI patch is based on is a bit old (5.5.0;
George), but I think some form of it still exists in the latest
codebase.

What we're seeing is that if the master host goes away during slave RRD
processing, it will prevent the slave XAPI from transitioning to master.
The patch adds a try-lock in the RRD backup so if the lock is still
held, the backup is skipped.


I'm wondering if this is a safe change (at least for 5.5.0), and if
anyone has ever run into this before?  (An unreliable way of generating
the situation is to pull the management link during a migration.)



Thanks for the help,

--
Ted M Lin

Attachment: api.hg-rrd_deadlock
Description: api.hg-rrd_deadlock

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