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https://issues.apache.org/jira/browse/WAGON-537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16735547#comment-16735547
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Olaf Otto commented on WAGON-537:
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Thanks [~michael-o]!
My hypothesis is that when maven is executed on a *nix derivate (Linux /
Mac...), the costs of java.io.Printstream.print(...) to the console can
besignificantly lower than on windows, thus this change does not contribute
much to the download speed, as it is already almost optimal. However, it the
change may still reduce CPU usage due to the reduced number of calls. I'll try
and test this on a *nix machine as soon as I have some time.
> Maven transfer speed of large artifacts is slow due to unsuitable buffer
> strategy
> ---------------------------------------------------------------------------------
>
> Key: WAGON-537
> URL: https://issues.apache.org/jira/browse/WAGON-537
> Project: Maven Wagon
> Issue Type: Improvement
> Components: wagon-http, wagon-provider-api
> Affects Versions: 3.2.0
> Environment: Windows 10, JDK 1.8, Nexus Artifact store > 100MB/s
> network connection.
> Reporter: Olaf Otto
> Assignee: Michael Osipov
> Priority: Major
> Labels: perfomance
> Fix For: 3.3.0, 3.3.1
>
> Attachments: wagon-issue.png
>
>
> We are using maven for build process automation with docker. This sometimes
> involves uploading and downloading artifacts with a few gigabytes in size.
> Here, maven's transfer 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.
> The same is true when uploding such an artifact.
> I have investigated the issue using JProfiler. The result shows an issue in
> AbstractWagon's transfer( Resource resource, InputStream input, OutputStream
> output, int requestType, long maxSize ) method used for remote artifacts and
> the same issue in AbstractHttpClientWagon#writeTo(OutputStream).
> 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.
> Now, the underlying InputStream implementation used in transfer will return
> calls to read(buffer, offset, length) as soon as *some* data is available.
> That is, fireTransferProgress may well be 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 transfers 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.
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