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https://issues.apache.org/jira/browse/PDFBOX-2882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14630447#comment-14630447
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Timo Boehme commented on PDFBOX-2882:
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Thanks for having a look at the code. I chose the usage of AtomicBoolean and
the synchronization deliberately to minimize synchronization overhead and to
minimize blocking of parallel access (while currently it may only be one thread
but this could be changed in the future and the memory backend should be
capable of handling this). The nice thing with AtomicBoolean is that it does
not use 'normal' synchronization and comes with lower overhead. Thus where
possible I use this, e.g. for 'isClosed'-checking so this is more lightweight
as synchronizing the whole method. Additionally if the page is in-memory the
read/write operation does not need any further synchronization which means it
can run in parallel providing very fast parallel page access to in-memory
pages. Only the file access needs to be synchronized. In principle the file I/O
is the operation which will take most of the time thus it is crucial that such
an operation does not block any other parallel page access not using the file.
I will have a look if using only one lock for isClosed+raf is enough without
sacrifying performance of parallel access.
> Improve performance when using scratch file
> -------------------------------------------
>
> Key: PDFBOX-2882
> URL: https://issues.apache.org/jira/browse/PDFBOX-2882
> Project: PDFBox
> Issue Type: Improvement
> Components: Parsing
> Affects Versions: 2.0.0
> Reporter: Timo Boehme
> Assignee: Timo Boehme
> Priority: Minor
> Attachments: ScratchFile.java, ScratchFileBuffer.java
>
>
> The current scratch file implementation uses many direct I/O calls which
> slows down parsing compared with in-memory scratch buffer considerably.
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