[Deploying Sakai] database connections disappearing

Charles Hedrick hedrick at rutgers.edu
Sun Nov 1 09:12:16 PST 2009

I went to 1.5.3 on one of 5 front ends a week ago. We just moved to it  
on all 5 yesterday. However it's not clear whether it's fixed what I  
wanted it to fix. I'm beginning to suspect that the pauses I'm trying  
to fix are due to paging. I'm going to try to make my JVM's a little  

On Nov 1, 2009, at 1:20:09 AM, David Horwitz wrote:

> Hi Chuck,
> Have you tried upgrading commons-pool? We've upgraded commons-pool  
> in the 1.1 kernel to 1.5.2 (we should go to 1.5.3) without any  
> noticeable problems. OOTB the 1.0 kernels are using commons-pool 1.3
> D
> Charles Hedrick wrote:
>> Since we moved from 2.5 to 2.6 I've been seeing databaSe  
>> connections disappear. We start out with 300. We have set up dbcp  
>> to keep a constant 300. However over time we start building up  
>> connections that dbcp thinks are in use, but never get returned.  
>> The rate is about 3 per day. The obvious suspicion would be that  
>> Sakai is getting a connection from the pool and not returning it.  
>> However doing "netstat" it's clear that the TCP connections are no  
>> longer open. I doubt that the server is closing them. It didn't in  
>> the past, and with a nearly idle front end we don't lose any. The  
>> amount we lose seems to be connected to activity. There's no way  
>> Sakai itself could be closing the TCP connection, since we don't  
>> set the option that lets the program access the underlying  
>> connection, and of course closing a pooled connection simply  
>> returns it to the pool. it looks to me like a malfunction in dbcp  
>> or pool. However it doesn't appear that dbcp has changed since 2.5.
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