« Return to Thread: Serious scalability issues with Oncourse at Indiana U
Re: dbcp vs c3p0 (was Re: Serious scalability issues with Oncourse at Indiana U)
by R.P. Aditya
::
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Do you have minIdle and maxIdle set? and does maxIdle = maxActive? That will
ensure you don't create new db connections and will help you scale much
better.
We have 8 appservers and use:
minIdle@...=1
maxIdle@...=14
initialSize@...=15
maxActive@...=14
with 400 requests per second peak, I'm don't see why you would
need 2400 db pool connections -- maybe 400 * 2 for safety, but you are just
eating PGA unnecessarily with all those connections, and that memory could be
used for SGA instead (we reduced our PGA from 512m to 256m and haven't seen
problems).
Adi
On Thu, Sep 06, 2007 at 03:13:39PM -0400, Lance Speelmon wrote:
> Adi,
>
> Let me see if I can outline the changes:
>
> 1) DBCP settings we have been running for 2+ years:
> minSize=10
> initialSize=10
> maxSize=50
>
> 2) When we started seeing DBCP having problems establishing new
> database connections, we switched to:
> minSize=50
> initialSize=50
> maxSize=50
> * These settings served us pretty well until we saw the 2x load
> increase the first week of classes.
>
> 3) Once the load really hit we tried:
> minSize=150
> initialSize=150
> maxSize=150
> * We were still seeing errors with creating new database connections
> and DBCP deadlocks.
>
> 4) Our current settings after switching to c3p0:
> minSize=150
> initialSize=150
> maxSize=150
> * We still saw connection errors, but c3p0 was able to cope without
> any deadlocking.
>
> 5) Now that we think we have resolved our Oracle connection issues,
> we are considering moving to the following settings for c3p0:
> minSize=10
> initialSize=10
> maxSize=150
> * The change that we think resolved the Oracle connection issues were
> increasing number of dispatchers, and disabling automatic memory
> management.
>
> Thanks, L
>
>
>
>
> Lance Speelmon +1 (317) 278-9053
> Manager Online Development / Sakai Release Manager
>
>
> On Sep 6, 2007, at 10:13 AM, R.P. Aditya wrote:
>
> >On Wed, Sep 05, 2007 at 04:26:34PM -0400, Lance Speelmon wrote:
> >> The first sign of trouble came from the fact that DBCP was having
> >> trouble obtaining and maintaining connections to Oracle. DBCP has a
> >> nasty bug that can be triggered in these kinds of conditions that
> >> results in a deadlock situation. To resolve the DBCP bugs, we
> >> switched to the c3p0 connection pool. C3p0 behaves much more stably
> >> and predictably under heavy load and can recover better from
> >> connection issues with Oracle. This is a drop-in replacement for
> >> DBCP and I am going to recommend that Sakai switch to this
> >connection
> >> pool as a default in the 2.5 release.
> >
> >what were the dbcp parameters you were using per appserver and what
> >are they
> >under c3p0?
> >
> >Any reason why did increasing the connection pool so drastically
> >helped?
> >
> >Thanks,
> >Adi
> >
>
> [see attachment: "message0.html", size: 4702 bytes]
>
> [see attachment: "smime.p7s", size: 2417 bytes]
>
>
> Attachments:
>
> message0.html
> https://collab.sakaiproject.org/access/content/attachment/66508027-ebfb-4f38-8041-bae67cfeeff3/message0.html
>
> smime.p7s
> https://collab.sakaiproject.org/access/content/attachment/6570e313-5eda-400e-80ae-1221d28f2725/smime.p7s
>
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ensure you don't create new db connections and will help you scale much
better.
We have 8 appservers and use:
minIdle@...=1
maxIdle@...=14
initialSize@...=15
maxActive@...=14
with 400 requests per second peak, I'm don't see why you would
need 2400 db pool connections -- maybe 400 * 2 for safety, but you are just
eating PGA unnecessarily with all those connections, and that memory could be
used for SGA instead (we reduced our PGA from 512m to 256m and haven't seen
problems).
Adi
On Thu, Sep 06, 2007 at 03:13:39PM -0400, Lance Speelmon wrote:
> Adi,
>
> Let me see if I can outline the changes:
>
> 1) DBCP settings we have been running for 2+ years:
> minSize=10
> initialSize=10
> maxSize=50
>
> 2) When we started seeing DBCP having problems establishing new
> database connections, we switched to:
> minSize=50
> initialSize=50
> maxSize=50
> * These settings served us pretty well until we saw the 2x load
> increase the first week of classes.
>
> 3) Once the load really hit we tried:
> minSize=150
> initialSize=150
> maxSize=150
> * We were still seeing errors with creating new database connections
> and DBCP deadlocks.
>
> 4) Our current settings after switching to c3p0:
> minSize=150
> initialSize=150
> maxSize=150
> * We still saw connection errors, but c3p0 was able to cope without
> any deadlocking.
>
> 5) Now that we think we have resolved our Oracle connection issues,
> we are considering moving to the following settings for c3p0:
> minSize=10
> initialSize=10
> maxSize=150
> * The change that we think resolved the Oracle connection issues were
> increasing number of dispatchers, and disabling automatic memory
> management.
>
> Thanks, L
>
>
>
>
> Lance Speelmon +1 (317) 278-9053
> Manager Online Development / Sakai Release Manager
>
>
> On Sep 6, 2007, at 10:13 AM, R.P. Aditya wrote:
>
> >On Wed, Sep 05, 2007 at 04:26:34PM -0400, Lance Speelmon wrote:
> >> The first sign of trouble came from the fact that DBCP was having
> >> trouble obtaining and maintaining connections to Oracle. DBCP has a
> >> nasty bug that can be triggered in these kinds of conditions that
> >> results in a deadlock situation. To resolve the DBCP bugs, we
> >> switched to the c3p0 connection pool. C3p0 behaves much more stably
> >> and predictably under heavy load and can recover better from
> >> connection issues with Oracle. This is a drop-in replacement for
> >> DBCP and I am going to recommend that Sakai switch to this
> >connection
> >> pool as a default in the 2.5 release.
> >
> >what were the dbcp parameters you were using per appserver and what
> >are they
> >under c3p0?
> >
> >Any reason why did increasing the connection pool so drastically
> >helped?
> >
> >Thanks,
> >Adi
> >
>
> [see attachment: "message0.html", size: 4702 bytes]
>
> [see attachment: "smime.p7s", size: 2417 bytes]
>
>
> Attachments:
>
> message0.html
> https://collab.sakaiproject.org/access/content/attachment/66508027-ebfb-4f38-8041-bae67cfeeff3/message0.html
>
> smime.p7s
> https://collab.sakaiproject.org/access/content/attachment/6570e313-5eda-400e-80ae-1221d28f2725/smime.p7s
>
> ----------------------
> This automatic notification message was sent by Sakai Collab
> (https://collab.sakaiproject.org/portal) from the WG: Production site.
> You can modify how you receive notifications at My Workspace > Preferences.
>
----------------------
This automatic notification message was sent by Sakai Collab (https://collab.sakaiproject.org/portal) from the DG: Development (a.k.a. sakai-dev) site.
You can modify how you receive notifications at My Workspace > Preferences.
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