[freenet-dev] r19683 - trunk/freenet/src/freenet/store

[Matthew Toseland]

On Friday 02 May 2008 16:24, Robert Hailey wrote:
> 
> On May 2, 2008, at 9:59 AM, j16sdiz at freenetproject.org wrote:
> 
> > Author: j16sdiz
> > Date: 2008-05-02 14:59:50 +0000 (Fri, 02 May 2008)
> > New Revision: 19683
> >
> > Modified:
> >   trunk/freenet/src/freenet/store/BerkeleyDBFreenetStore.java
> > Log:
> > oomhook: lower database cache size
> >
> >
> > Modified: trunk/freenet/src/freenet/store/BerkeleyDBFreenetStore.java
> > ===================================================================
> > --- trunk/freenet/src/freenet/store/BerkeleyDBFreenetStore.java	 
> > 2008-05-02 14:59:29 UTC (rev 19682)
> > +++ trunk/freenet/src/freenet/store/BerkeleyDBFreenetStore.java	 
> > 2008-05-02 14:59:50 UTC (rev 19683)
> > @@ -25,6 +25,7 @@
> > import com.sleepycat.je.DatabaseNotFoundException;
> > import com.sleepycat.je.Environment;
> > import com.sleepycat.je.EnvironmentConfig;
> > +import com.sleepycat.je.EnvironmentMutableConfig;
> > import com.sleepycat.je.LockMode;
> > import com.sleepycat.je.OperationStatus;
> > import com.sleepycat.je.RunRecoveryException;
> > @@ -2247,6 +2248,11 @@
> > 			keysFC.force(true);
> > 		if (lruFC != null)
> > 			lruFC.force(true);
> > +		
> > +		EnvironmentMutableConfig dbmc = environment.getMutableConfig();
> > +		long cacheSize = (long) (dbmc.getCacheSize() * .9); // we have 6  
> > databases, 0.9^6 = 0.53
> > +		dbmc.setCacheSize(cacheSize);
> > +		Logger.normal(this, "low memory, set db cache = " + cacheSize);
> > 	}
> >
> 
> What is the significance of 0.9^6=0.53? It seems to me if you are  
> trying to half the memory usage, all the caches would have to be  
> reduced by 0.5; otherwise the comment could be made a bit more clear.

Be careful not to adjust it down to zero. Setting the max database memory to 0 
currently sets it unlimited, resulting in full GCs every <10 seconds which 
last for ~ 3 seconds...
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