[SR-6450] Leak in Process on Linux

[swift-ci]

Previous ID	SR-6450
Radar	None
Original Reporter	oc243 (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Environment

DEVELOPMENT-SNAPSHOT-2017-11-16-a

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	@spevans
Priority	Medium

md5: 48142a06d97c0f16ee65fee7f8fd4f74

Issue Description:

The following foundation code seems to leak in Linux and I don't think that it should:

import Foundation

func process() {
    while true {
        let p = Process()
        p.launchPath = "/bin/true"
        p.launch()
        p.waitUntilExit()
    }
}

process()

Running Valgrind on this states:

==2562== 144,536 (71,659 direct, 72,877 indirect) bytes in 203 blocks are definitely lost in loss record 148 of 150
==2562==    at 0x4C2DBF6: malloc (vg_replace_malloc.c:299)
==2562==    by 0x52EAD75: swift_slowAlloc (in /home/oliver/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2017-11-16-a/usr/lib/swift/linux/libswiftCore.so)
==2562==    by 0x52EADAE: _swift_allocObject_ (in /home/oliver/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2017-11-16-a/usr/lib/swift/linux/libswiftCore.so)
==2562==    by 0x59D485F: Foundation.Process.__allocating_init() -> Foundation.Process (in /home/oliver/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2017-11-16-a/usr/lib/swift/linux/libFoundation.so)
==2562==    by 0x10A36A: main.process() -> () (in /home/oliver/main)
==2562==    by 0x1099D3: main (in /home/oliver/main)

[spevans]

The runLoopSource was creating a retain cycle so it needed to be set to nil when the child process had finished.

#2631 should fix it.