[SR-11854] OperationQueue not asynchronous

[swift-ci]

Previous ID	SR-11854
Radar	rdar://problem/57549294
Original Reporter	ZakMcK (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Attachment: Download

Environment

Swift Runtime

Swift version 5.1 (swift-5.1.2-RELEASE)
Target: x86_64-unknown-linux-gnu

OS

Additional Detail from JIRA

Votes	0
Component/s	Foundation, libdispatch
Labels	Bug
Assignee	@lxbndr
Priority	Medium

md5: 7ac99bf05c7d6c768f6910f21d555ebb

Issue Description:

I have a problem with the OperationQueue in the swift-5.1.2-RELEASE version. The whole OperationQueue seems to work synchronously with one single thread instead of using all available cores.

This worked with swift 5.0. Following example

let testQueue = OperationQueue()
testQueue.name = "TestAsync"
testQueue.maxConcurrentOperationCount = 4

for _ in 0...10 {
    testQueue.addOperation { 
        print("added \(Thread.current) on \(OperationQueue.current?.underlyingQueue?.label ?? "None")")
        //Thread.sleep(forTimeInterval: 1)
    }
    //print("OP COUNT: \(testQueue.operationCount)")
}

testQueue.waitUntilAllOperationsAreFinished()

yields this output

Hello, world!
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
OP COUNT: 1
done pushing operations
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None
added <Thread: 0x00007f8e14000c80> on None

I would assume that different threads should be incorporated (maxConcurrentOperationCount is set to 4).

[beccadax]

@swift-ci create

[lxbndr]

apple/swift-corelibs-foundation#2937