Re: Question on TemplateCache synchronization

Is this just a coincidence that you ask it now? Because, the reworked
caching system was committed only like days ago. It's much more
multi-core friendly now. Grab the HEAD of the 2.3 branch from
https://freemarker.svn.sourceforge.net/svnroot/freemarker/branches/2.3/freemarker
and give it a try. (I wanted to say to grab the latest nightly build
jar, but it seems that service is down at the moment.)

Thursday, April 10, 2008, 12:19:06 AM, Bruce Ritchie wrote:

> I'm currently analyzing a thread dump from a production environment
> where I have 100 threads in waiting on the CacheStorage lock in
> TemplateCache:
>
> at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:246)
> - waiting to lock <0x27445a20> (a freemarker.cache.MruCacheStorage)
> at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:229)
> at
> freemarker.template.Configuration.getTemplate(Configuration.java:487)
> at
> freemarker.template.Configuration.getTemplate(Configuration.java:452)
>
> and one thread actually holding the lock:
>
> at java.lang.Throwable.fillInStackTrace(Native Method)
> at java.lang.Throwable.<init>(Throwable.java:196)
> at java.lang.Exception.<init>(Exception.java:41)
> at javax.naming.NamingException.<init>(NamingException.java:109)
> at
> org.apache.naming.resources.FileDirContext.lookup(FileDirContext.java:208)
> at
> org.apache.naming.resources.ProxyDirContext.lookup(ProxyDirContext.java:294)
> at
> org.apache.catalina.loader.WebappClassLoader.findResourceInternal(WebappClassLoader.java:1891)
> at
> org.apache.catalina.loader.WebappClassLoader.findResource(WebappClassLoader.java:934)
> at
> org.apache.catalina.loader.WebappClassLoader.getResource(WebappClassLoader.java:1069)
> at
> com.jivesoftware.community.util.ChainingClassLoader.getResource(ChainingClassLoader.java:91)
> at
> com.jivesoftware.community.web.struts.JiveClassTemplateLoader.getURL(JiveClassTemplateLoader.java:27)
> at
> freemarker.cache.URLTemplateLoader.findTemplateSource(URLTemplateLoader.java:75)
> at
> freemarker.cache.MultiTemplateLoader.findTemplateSource(MultiTemplateLoader.java:111)
> at
> freemarker.cache.TemplateCache.acquireTemplateSource(TemplateCache.java:520)
> at
> freemarker.cache.TemplateCache.findTemplateSource(TemplateCache.java:510)
> at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:315)
> - locked <0x27445a20> (a freemarker.cache.MruCacheStorage)
> at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:229)
> at
> freemarker.template.Configuration.getTemplate(Configuration.java:487)
> at
> freemarker.template.Configuration.getTemplate(Configuration.java:452)
>
>
> Is there really a good reason for synchronizing on the CacheStorage?
>>From my reading of the code there might be a small race between
> storage.get()l and storage.remove() but I'm not sure it's really worth
> synchronizing for. Am I wrong in this statement? If so, can someone
> suggest an alternate approach that doesn't require synchronization? In
> production we set the templateUpdateDelay to Integer.MAX_VALUE so
> basically we should never have to worry about the template changing or
> being removed after it's loaded.
>
>
> Regards,
>
> Bruce Ritchie
>
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-- 
Best regards,
 Daniel Dekany


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