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https://issues.apache.org/jira/browse/WAGON-537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16649964#comment-16649964
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ASF GitHub Bot commented on WAGON-537:
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olaf-otto opened a new pull request #50: WAGON-537 Maven download speed of
large artifacts is slow
URL: https://github.com/apache/maven-wagon/pull/50
Introduced a blocking buffer strategy that will give filling up the buffer
priority to reduce the number of fireTransferProgress invocations.
Introduced a method to dynamically allocate a buffer size better suited for
the expected amount of transferred data.
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> Maven download speed of large artifacts is slow due to unsuitable buffer
> strategy for remote Artifacts in AbstractWagon
> -----------------------------------------------------------------------------------------------------------------------
>
> Key: WAGON-537
> URL: https://issues.apache.org/jira/browse/WAGON-537
> Project: Maven Wagon
> Issue Type: Improvement
> Components: wagon-provider-api
> Affects Versions: 3.2.0
> Environment: Windows 10, JDK 1.8, Nexus Artifact store > 100MB/s
> network connection.
> Reporter: Olaf Otto
> Priority: Major
> Labels: perfomance
> Attachments: wagon-issue.png
>
>
> We are using maven for build process automation with docker. This sometimes
> involves downloading images with a few gigabytes in size. Here, maven's
> download speed is consistently and reproducibly slow. For instance, an
> artifact with 7,5 GB in size took almost two hours to transfer in spite of a
> 100 MB/s connection with respective reproducible download speed from the
> remote nexus artifact repository when using a browser to download.
> I have investigated the issue using JProfiler. The result clearly shows a
> significant issue in AbstractWagon's transfer( Resource resource, InputStream
> input, OutputStream output, int requestType, long maxSize ) method used for
> remote artifacts.
> Here, the input stream is read in a loop using a 4 Kb buffer. Whenever data
> is received, the received data is pushed to downstream listeners via
> fireTransferProgress. These listeners (or rather consumers) perform
> expensive tasks such as checksumming or printing to console.
> Now, the underlying InputStream implementation used in transfer will return
> calls to read(bugger, offset, length) as soon as *some* data is available.
> That is, fireTransferProgress is invoked with an average number of bytes less
> than half the buffer capacity (this varies with the underlying network and
> hardware architecture). Consequently, fireTransferProgress is invoked
> *millions of times* for large files. As this is a blocking operation, the
> time spent in fireTransferProgress dominates and drastically slows down the
> transfer by at least one order of magnitude.
> !wagon-issue.png!
> In our case, we found download speed reduced from a theoretical optimum of
> ~80 seconds to to more than 3200 seconds.
> From an architectural perspective, I would not want to make the consumers /
> listeners invoked via fireTransferProgress aware of their potential impact on
> download speed, but rather refactor the transfer method such that it uses a
> buffer strategy reducing the the number of fireTransferProgress invocations.
> This should be done with regard to the expected file size of the transfer,
> such that fireTransferProgress is invoked often enough but not to frequent.
> I have implemented a solution and transfer speed went up more than one order
> of magnitude. I will provide a pull request asap.
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