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From "Naumova Natalya (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5277) [startup][performance]
Date Mon, 10 Dec 2007 08:06:46 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12549959
] 

Naumova Natalya  commented on HARMONY-5277:
-------------------------------------------

Can anyone review some of these optimization, please? Of course they need a deep revision,
but it can be a good start for startup improvement.

Also I want pay attention on HARMONY-4569 filed by Gregory Shimansky some time ago : "Ineffecient
manifest parsing results in slowdown when debugging java code" - the key is in lib/boot/bcprov.jar
that is signed. It's read via java classloader (not vm), so the  big amount of Ljava/io/ByteArrayOutputStream;.write(I)V
calls (it is called 131114 times - it equals the size of bcprov.jar manifest) is reading bcprov.jar
manifest reading byte by byte. The tries to rewrite  java.util.jar.InitManifest to read the
manifest by line failed (degradation in performance), but moving bcprov.jar to bootclasspath
gives ~7% on HelloWorld startup. 

The second problem is in ZipEntry reading: some of JarEntry's are reading twice : resources
in jars for instance. Besides reading jar entries is not effective : it's reading via classlib
portlib, that uses systems calls always and there is no cashing of entries that were read
before. 

> [startup][performance]
> ----------------------
>
>                 Key: HARMONY-5277
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5277
>             Project: Harmony
>          Issue Type: Improvement
>          Components: DRLVM
>            Reporter: Naumova Natalya 
>         Attachments: classloading.patch, jarmapping.BCP.patch, uncompressed_BCP_jars.classlib.patch,
uncompressed_BCP_jars.vm.patch
>
>
> Some general improvements for VM startup will be collected here. Optimizations are for
both DRLVM and CLASSLIB. 

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