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From Todd Lipcon <t...@cloudera.com>
Subject Re: deadlock between split and delete
Date Thu, 30 Sep 2010 20:00:34 GMT
RWLock can indeed deadlock with itself - it doesn't support "lock
upgrade" from read to write.


On Thu, Sep 30, 2010 at 12:14 PM, Ryan Rawson <ryanobjc@gmail.com> wrote:
> What jvm version are you using? A readwrite lock should not be able to
> deadlock on itself like that. There has been known jvm bugs involving locks
> alas...
> On Sep 30, 2010 12:09 PM, "Matt Corgan" <mcorgan@hotpads.com> wrote:
>> I'm inserting several million rows of a table that has ~50 columns, 31 of
>> which are days of the month and are often null. For the null ones I issue
> a
>> delete instead of a put to make sure any previous data in that column gets
>> deleted. I'm inserting 1000 rows at a time, so the behavior is to put ~40k
>> cells, delete ~10k cells, and then flush. I've also tried flushing between
>> the puts and deletes.
>> This works fine until the region tries to split, at which point i almost
>> always get a deadlock. I suspect it's similar to these:
>> https://issues.apache.org/jira/browse/HBASE-2097
>> https://issues.apache.org/jira/browse/HBASE-2915
>> Here are the 2 threads in question from the regionserver:
>> http://pastebin.com/ddVbHxvP
>> And the regionserver log (split starts at line 38):
>> http://pastebin.com/JgvchvYK
>> This happens in both 0.20.6 and 0.89.20100726. 5 GB heap, and servers are
>> idle other than this.
>> If there is actually a deadlock, do you think that waiting x milliseconds
>> between the puts and the deletes could be a temporary workaround?
>> Thanks,
>> Matt

Todd Lipcon
Software Engineer, Cloudera

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