sebb wrote:
> On 12/01/2010, Phil Steitz <phil.ste...@gmail.com> wrote:
>> sebb wrote:
>>  > On 11/01/2010, Phil Steitz <phil.ste...@gmail.com> wrote:
>>  >> Phil Steitz wrote:
>>  >>  > Posting the last failed build output while it is, um....still 
>> available:
>>  >
>>  > I assume this is from:
>>  >
>>  > 
>> http://vmbuild.apache.org/continuum/buildResult.action?buildId=267625&projectId=22
>>  >
>>  >>  >
>>  >>  > Multithread test time = 489 ms. Threads: 20. Loops: 20. Hold time:
>>  >>  > 200. Maxwait: 100. Done: 11. Did not run: 0. Failed: 9. expectError:
>>  >>  > true
>>  >>  > StartupDelay: 0. ConnectTime: 3. Runtime: 203. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: 132. Runtime: 333. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 42. ConnectTime: 90. Runtime: 290. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: 90. Runtime: 291. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 76. ConnectTime: 14. Runtime: 215. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 13. ConnectTime: 1. Runtime: 202. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 16. ConnectTime: 0. Runtime: 200. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 1. ConnectTime: 0. Runtime: 200. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 11. ConnectTime: 0. Runtime: 200. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 18. ConnectTime: 0. Runtime: 201. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 7. ConnectTime: 17. Runtime: 218. Loops: 1. State:
>>  >>  > Done. thrown: null. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 101. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 1. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 101. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 1. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  > StartupDelay: 0. ConnectTime: -. Runtime: 100. Loops: 1. State:
>>  >>  > Getting Connection. thrown:
>>  >>  > org.apache.commons.dbcp.SQLNestedException: Could not retrieve
>>  >>  > connection info from pool. (using nanoTime)
>>  >>  >
>>  >>  > There are three things that look odd here.  First is that the second
>>  >>  > successful thread should have failed with a timeout.  That may be
>>  >>  > explainable by "wakeup delay."  The second is that unless
>>  >>  > startupDelay is not reliable, the allocation looks unfair and pool
>>  >>  > 1.5 is supposed to implement fairness - i.e., it should be the
>>  >>  > threads with lower startupDelays that are served first.
>>  >>
>>  >>
>>  >> Scratch that.  pooledConnectionAndInfo has a synch block before the
>>  >>  call to borrowObject to create or acquire the pool.  All threads are
>>  >>  going after the same pool.  The first one in has to create the pool.
>>  >>
>>  >
>>  > It's rather odd.
>>  >
>>  > The successful threads all took 200+ms to complete, during which time
>>  > there should be no spare connections available.
>>  >
>>  > Yet the second thread only appears to have waited 132ms to get the 
>> connection.
>>  > [Which should have caused a timeout error, but perhaps that's excusable.]
>>  > However, it should not be possible to aquire the 11th connection in
>>  > less than 200ms.
>>  > What happened to that thread?
>>  > Did it somehow stall before waiting for the connection?
>>  > If so, why is the overall runtime for the thread only 333ms?
>>  >
>>  > I will add some more info to the debug output.
>>
>>
>> Still no failures.  This weekend, NTP was re-enabled on vmbuild. It
>>  had been disabled for some time.
> 
> I think at least one build failed after the time was corrected:
> 
> http://vmbuild.apache.org/continuum/buildResult.action?projectId=22&projectGroupId=22&projectName=&buildId=267564
> 
> Anyway, the test depends on relative time, rather than absolute time,
> so the true time is surely irrelevant?

The true time, yes; but if any of this affects measures of elapsed
time differentially across threads, that would cause problems.
> 
> Perhaps if the clock was running extremely slowly or very fast it
> might cause JVM scheduling issues, but otherwise I don't see how it
> could affect the test.
> 
>>  As I said above, loaded guests running under Vmware are known to
>>  lose clock accuracy.  See [1], [2].
> 
> BTW, both URLs are the same.
> 
>>  [1]
>>  
>> http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006072
>>  [2]
>>  
>> http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006072

I meant
http://www.vmware.com/pdf/vmware_timekeeping.pdf
>>
>>
>>  Phil
>>
>>
>>
>>  >
>>  >>  Phil
>>  >>
>>  >>
>>  >>
>>  >>   This could
>>  >>  > point to a pool bug. Finally, the connectTimes for some of the
>>  >>  > successful threads are way too long.
>>  >>  >
>>  >>  > Phil
>>  >>
>>  >>
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