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https://issues.apache.org/jira/browse/COMPRESS-485?focusedWorklogId=240671&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-240671
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ASF GitHub Bot logged work on COMPRESS-485:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 11/May/19 20:42
Start Date: 11/May/19 20:42
Worklog Time Spent: 10m
Work Description: Tibor17 commented on pull request #78: COMPRESS-485
keep zip entries order in parallel zip creation
URL: https://github.com/apache/commons-compress/pull/78#discussion_r283110877
##########
File path:
src/main/java/org/apache/commons/compress/archivers/zip/ParallelScatterZipCreator.java
##########
@@ -255,8 +257,13 @@ public void writeTo(final ZipArchiveOutputStream
targetStream)
compressionDoneAt = System.currentTimeMillis();
synchronized (streams) {
+ // write zip entries in the order they were added (kept as
futures)
+ for (final Future<ScatterZipOutputStream> future : futures) {
Review comment:
This loop was added. And it is a problem in this synchronized block.
The monitor lock is `streams` and not `futures`. They cannot be both in one
statement.
Problem: this will cause NPE when the CPU is overloaded. The same issue was
fixed in Surefire (see memory model).
Additionally the `futures.add()` is not synchronized!
One way would be for you to introduce double synchro block.
I would not do it! Instead I would avoid synchronizations of `ArrayList` and
on both. Then I would use modern collections which do not need external
synchronizatrions (i.e. `Collections.synch...`) and this way there would not
be any `synchronized`. Use `ConcurrentLinkedDequeue`. It is useful when you add
to the tail of the queue and do not remove, and if you iterate, because this
implementation safely iterates even if you change it : no issue.
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Issue Time Tracking
-------------------
Worklog Id: (was: 240671)
Time Spent: 1h 20m (was: 1h 10m)
> Reproducible Builds: keep entries order when gathering ScatterZipOutputStream
> content in ParallelScatterZipCreator
> ------------------------------------------------------------------------------------------------------------------
>
> Key: COMPRESS-485
> URL: https://issues.apache.org/jira/browse/COMPRESS-485
> Project: Commons Compress
> Issue Type: Improvement
> Components: Archivers
> Affects Versions: 1.18
> Reporter: Hervé Boutemy
> Priority: Major
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> currently, zip files created using ParallelScatterZipCreator have random
> order.
> This is causing issues when trying to do Reproducible Builds with Maven
> MNG-6276
> Studying ParallelScatterZipCreator, entries are kept sorted in memory in
> futures list: instead of writing each full scatter in sequence, iterating
> over futures should permit to write each zip entry in original order, without
> changing the API or any performance of the gathering process
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