[ http://issues.apache.org/jira/browse/DERBY-801?page=comments#action_12443040 ] Knut Anders Hatlen commented on DERBY-801: ------------------------------------------
I'm wondering whether we should change the DEBUG_PRINT calls to ASSERT/THROWASSERT. Falling back to the old implementation on errors is a good approach in insane mode, but I think the errors should be exposed in sane mode so we can see them and fix them. After running the JUnit tests (java junit.textui.TestRunner org.apache.derbyTesting.functionTests.suites.All) I noticed that derby.log contained this message (but no tests failed): DEBUG RAFContainerFactory OUTPUT: Caught exception when setting up rafContainerConstructor > Allow parallel access to data files. > ------------------------------------ > > Key: DERBY-801 > URL: http://issues.apache.org/jira/browse/DERBY-801 > Project: Derby > Issue Type: Improvement > Components: Performance, Store > Affects Versions: 10.0.2.0, 10.0.2.1, 10.1.1.0, 10.1.2.1 > Environment: Any > Reporter: Øystein Grøvlen > Assigned To: Anders Morken > Attachments: DERBY-801-v2.patch, DERBY-801-v3.patch, > DERBY-801-v4.patch, NIO-RAFContainer-v1.patch > > > Derby currently serializes accesses to a data file. For example, the > implementation of RAFContainer.readPage is as follows: > synchronized (this) { // 'this' is a FileContainer, i.e. a file object > fileData.seek(pageOffset); // fileData is a RandomAccessFile > fileData.readFully(pageData, 0, pageSize); > } > I have experiemented with a patch where I have introduced several file > descriptors (RandomAccessFile objects) per RAFContainer. These are > used for reading. The principle is that when all readers are busy, a > readPage request will create a new reader. (There is a maximum number > of readers.) With this patch, throughput was improved by 50% on > linux. For more discussion on this, see > http://www.nabble.com/Derby-I-O-issues-during-checkpointing-t473523.html > The challenge with the suggested approach is to make a mechanism to > limit the number of open file descpriptors. Mike Matrigali has > suggested to use the existing CacheManager infrastructure for this > purpose. For a discussion on that, see: > http://www.nabble.com/new-uses-for-basic-services-cache---looking-for-advice-t756863.html -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
