[SR-4201] DispatchSourceSignal doesn't work properly on Linux #695

weissi · 2017-03-09T01:19:03Z


Previous ID	SR-4201
Radar	None
Original Reporter	@weissi
Type	Bug
Status	Resolved
Resolution	Done

Attachment: Download

Additional Detail from JIRA


Votes	0
Component/s	libdispatch
Labels	Bug
Assignee	dgrove-oss (JIRA)
Priority	Medium

md5: cb7e513f2c891ab499ed2e68f4d8a5f4

Issue Description:

Description

Signals don't get delivered on `DispatchSourceSignal` on Linux. As a repro, run the following program

#if os(Linux)
import Glibc
#else
import Darwin
#endif
import Dispatch

let sig = SIGCHLD

signal(sig, SIG_IGN);
let q = DispatchQueue(label: "foo")
let s = DispatchSource.makeSignalSource(signal: sig, queue: q)
s.setEventHandler {
    print("SIGNAL")
    fputs("SIGNAL!\n", stderr)
    kill(getpid(), SIGKILL)
}
s.setRegistrationHandler {
    print("registered in pid \(getpid())")
    print("kill -\(sig) \(getpid())")
}
s.resume()
dispatchMain()

and then execute the line that it writes ("kill -...")

on macOS

$ ./test & 
[1] 49783
registered in pid 49783
kill -20 49783
$ kill -20 49783
SIGNAL
SIGNAL!
[1]+  Killed: 9               ./test
$

as expected, the program prints "SIGNAL", then "SIGNAL!" and then kills itself.

On Linux

$ ./test &
[1] 28406
registered in pid 28406
kill -17 28406
$ kill -17 28406
$ kill -17 28406
$ kill -17 28406
$ kill -17 28406

and nothing happens, the program is still alive. Interestingly, in LLDB on Linux is sometimes does receive the signal

On Linux in LLDB

$ lldb ./test
(lldb) target create "./test"
Current executable set to './test' (x86_64).
(lldb) run
Process 28461 launched: './test' (x86_64)
registered in pid 28461
kill -17 28461
Process 28461 stopped and restarted: thread 1 received signal: SIGCHLD
SIGNAL
SIGNAL!
Process 28461 exited with status = 9 (0x00000009) 
(lldb)

(the kill was run from some other terminal here).

Swift versions:

macOS

$ swiftc --version
Apple Swift version 3.0.2 (swiftlang-800.0.63 clang-800.0.42.1)
Target: x86_64-apple-macosx10.9

Linux

swiftc --version
Swift version 3.0.2 (swift-3.0.2-RELEASE)
Target: x86_64-unknown-linux-gnu

but this also happens with this Swift version

swiftc --version
Swift version 3.1-dev (LLVM 5c165fb715, Clang e540ba0c30, Swift 3d3fdecbb4)
Target: x86_64-unknown-linux-gnu

which is master from 1st Feb 2017

The text was updated successfully, but these errors were encountered:

swift-ci · 2017-03-09T13:16:01Z