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From Karl Wright <>
Subject Re: Postgresql Performance Issue (deadlock) with Document Fetch
Date Thu, 01 Dec 2016 11:10:17 GMT
Hi Chalitha,

I have honestly never heard of anything so bizarre before.

We have performance tests for some connectors that run 100,000 documents or
more.  If what you are encountering is postgresql related, you could try to
run them against your postgresql instance and see what happens.  That would
at least point in the right direction.  But this involves a bit of work.

To do this:

- start with the source distribution
- add the postgresql driver in the right spot
- Modify the superuser name/password in the class
- Add whatever is needed to point to the right postgresql instance in the
same package, by overriding writeProperties() in the same class
- Run "ant load-pg" to kick it off

You can also try the diagnostic route: when there's a deadlock that is
unexpected, there's often a stack trace too in the manifoldcf.log.

Finally, it's possible that what's happening is that you're hitting the
maximum transaction count for the postgresql database.  This used to be way
larger than 34000 -- it used to be something like 2000000000.  But perhaps
there is a postgresql bug where that's no longer the case.  You might be
able to test this theory by running until the database halts and then
shutting down manifoldcf and run "VACUUM FULL" on the database.  That will
(I think) reset everything.  If all is good after that, you know the
problem has to be in the postgresql world.  Probably though it is something
wrong in the configuration.  I'm very interested to learn what is happening
here.  Please let me know.  FWIW, I run the windows version of 9.3 here and
see no issues like this on my crawls.

There's one last thing you could try, if everything seems to work with your
postgresql instance and it seems like it's only the alfresco connector that
messes stuff up.  When it freezes up, before it dies, get a thread dump of
the manifoldcf agents process.  Send that to me and I can tell what's


On Thu, Dec 1, 2016 at 4:25 AM, Chalitha Perera <> wrote:

> Hi All,
> We are trying Alfresco enterprise 5.0.1 with ManifoldCF 2.5 configured with
> postgresql 9.3. For postgres we use the configs given in [1]. From manifold
> side
> maxhandles = 105
> crawler threads = 50
> In alfresco connector max connections = 10
> The problem is that when the documents get fetched it gets stuck when a
> certain number of documents are fetched. The job always get stuck when
> 34227 documents are fetched and after some long wait it gives the database
> error.
> *Exception tossed: ERROR: deadlock detected  Detail: Process 5214 waits for
> ShareLock on transaction 155292; blocked by process 18781.Process 18781
> waits for ShareLock on transaction 155295; blocked by process 5214.*
> When I restarted the manifold and postgres again only very few documents
> gets fetched.
> Any tips on resolving this deadlock issue is greatly appreciated.
> [1]
> performance-tuning.html
> Thanks,
> Chalitha
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