bugGNU Parallel - Bugs: bug #63090, --compress --keep-order together...


bug #63090: --compress --keep-order together can cause thousands of processes to spawn

Submitter:  John <johncs>
Submitted:  Thu 22 Sep 2022 04:59:57 AM UTC
Category:  None Severity:  3 - Normal
Item Group:  None Status:  Fixed
Privacy:  Public Assigned to:  tange
Open/Closed:  Closed
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Sun 23 Apr 2023 08:19:00 AM UTC, comment #2: 

Now part of documentation.

Ole Tange <tange>
Group administrator
Wed 28 Sep 2022 11:55:06 PM UTC, comment #1: 

Yep. That is by design.

It should probably be mentioned under `--compress` and explained in `man parallel_design`.

Ole Tange <tange>
Group administrator
Thu 22 Sep 2022 04:59:57 AM UTC, original submission:  

The key ingredients seems to be --compress and --keep-order together, plus a task that takes awhile. Here is a simple reproduction:

# WARNING: This will cause thousands of processes to spawn
yes 0 | head -n 400 | xargs parallel --keep-order --compress sleep ::: 5

Try running `watch "ps | wc -l"` in another terminal window to see the number of processes explode.

Here's some version information about my environment:

$ parallel --version
GNU parallel 20220822
$ sw_vers
ProductName:        macOS
ProductVersion:        12.5.1
BuildVersion:        21G83

John <johncs>


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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2023-04-23 tange StatusIn Progress Fixed
        Open/ClosedOpen Closed
    2022-09-28 tange StatusNone In Progress
        Assigned toNone tange

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