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[SR-14973] withTaskGroup leaks memory for every task added to the group #57315

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swift-ci opened this issue Jul 25, 2021 · 5 comments
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[SR-14973] withTaskGroup leaks memory for every task added to the group #57315

swift-ci opened this issue Jul 25, 2021 · 5 comments
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@ktoso
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. concurrency Feature: umbrella label for concurrency language features standard library Area: Standard library umbrella

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@swift-ci
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Previous ID SR-14973
Radar rdar://problem/81130259
Original Reporter Orobio (JIRA User)
Type Bug
Status Resolved
Resolution Done
Environment

swift-5.5-DEVELOPMENT-SNAPSHOT-2021-07-23-a-ubuntu20.04

Additional Detail from JIRA
Votes 0
Component/s Standard Library
Labels Bug, Concurrency
Assignee @ktoso
Priority Medium

md5: 4b6e62352672f083453f505793e86e64

relates to:

  • SR-15175 withTaskGroup(of:) leaks huge amounts of memory on linux

Issue Description:

Memory is malloc'ed for every task in the TaskGroup, which is never released.

The following:

await withTaskGroup(of: Int.self) { group in
    for i in 1...1234 {
        group.addTask { return i }
    }

    while let result = await group.next() {
        print(result)
    }
}

Results in:

valgrind --tool=memcheck --leak-check=full --show-leak-kinds=all .build/debug/TestApp
...
...
414,624 bytes in 1,234 blocks are still reachable in loss record 48 of 48
    at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
    by 0x4E2B917: swift_task_create_common (in /usr/lib/swift/linux/libswift_Concurrency.so)
    by 0x185CCF: $sScG7addTask8priority9operationyScPSg_xyYaYbcntF (<compiler-generated>:0)
    by 0x188E0C: $s7TestApp8runGroupSSyYaFyScGySiGzYaXEfU_ (main.swift:18)
    by 0x4E294EA: swift::runJobInEstablishedExecutorContext(swift::Job*) (in /usr/lib/swift/linux/libswift_Concurrency.so)
    by 0x4E29C87: swift_job_run (in /usr/lib/swift/linux/libswift_Concurrency.so)
    by 0x4EAE2A6: _dispatch_worker_thread (in /usr/lib/swift/linux/libdispatch.so)
    by 0x5864608: start_thread (pthread_create.c:477)
    by 0x59FE292: clone (clone.S:95)
...
...
@typesanitizer
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@ktoso
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ktoso commented Sep 3, 2021

Working on a fix here: #39158

@tayloraswift
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possibly related: SR-15175

@ktoso
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ktoso commented Sep 14, 2021

It was two separate issues, one fixed by #39158 and the other (including SR-15175 causing) fixed by #39295

@ktoso
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ktoso commented Sep 14, 2021

Resolved by:

Will be fixed in 5.5 too.

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
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@ktoso ktoso

Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. concurrency Feature: umbrella label for concurrency language features standard library Area: Standard library umbrella
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@ktoso @tayloraswift @typesanitizer @swift-ci