std::thread memory leaks

[emaxx-google]

Sample program:

#include <thread>
int main() {
  std::thread([]{}).detach();
}

Compilation flags:

emcc main.cc -pthread -fsanitize=address -s INITIAL_MEMORY=134217728 -s EXIT_RUNTIME=1

Result (Emscripten 2.0.9):

=================================================================
==42==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x22f9f in wasm-function[675]+0x22f9f (a.out.wasm+0x22f9f)
    #1 0x1840 in wasm-function[57]+0x1840 (a.out.wasm+0x1840)
    #2 0x166d in wasm-function[56]+0x166d (a.out.wasm+0x166d)
    #3 0x3b9a in wasm-function[123]+0x3b9a (a.out.wasm+0x3b9a)
    #4 0x80000510  (JavaScript+0x510)
    #5 0x80001bd0 in callMain a.out.js:7120:13
    #6 0x80001bf6 in doRun a.out.js:7158:21
    #7 0x80001c02 in run a.out.js:7170:3

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x22f9f in wasm-function[675]+0x22f9f (a.out.wasm+0x22f9f)
    #1 0x8dd4 in wasm-function[225]+0x8dd4 (a.out.wasm+0x8dd4)
    #2 0x182c in wasm-function[57]+0x182c (a.out.wasm+0x182c)
    #3 0x166d in wasm-function[56]+0x166d (a.out.wasm+0x166d)
    #4 0x3b9a in wasm-function[123]+0x3b9a (a.out.wasm+0x3b9a)
    #5 0x80000510  (JavaScript+0x510)
    #6 0x80001bd0 in callMain a.out.js:7120:13
    #7 0x80001bf6 in doRun a.out.js:7158:21

Indirect leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x22f9f in wasm-function[675]+0x22f9f (a.out.wasm+0x22f9f)
    #1 0x1825 in wasm-function[57]+0x1825 (a.out.wasm+0x1825)
    #2 0x166d in wasm-function[56]+0x166d (a.out.wasm+0x166d)
    #3 0x3b9a in wasm-function[123]+0x3b9a (a.out.wasm+0x3b9a)
    #4 0x80000510  (JavaScript+0x510)
    #5 0x80001bd0 in callMain a.out.js:7120:13
    #6 0x80001bf6 in doRun a.out.js:7158:21
    #7 0x80001c02 in run a.out.js:7170:3

SUMMARY: AddressSanitizer: 32 byte(s) leaked in 3 allocation(s).

[emaxx-google]

Symbolized traces (obtained with -O0 -g3):

=================================================================
==42==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x22f62 in operator new(unsigned long)+0x22f62 (a.out.wasm+0x22f62)
    #1 0x1803 in std::__2::thread::thread<main::$_0, void>(main::$_0&&) ../emsdk/upstream/emscripten/system/include/libcxx/thread:297:13
    #2 0x1630 in __original_main main-thread.cc:3:3
    #3 0x3b5d in main+0x3b5d (a.out.wasm+0x3b5d)
    #4 0x80000510  (JavaScript+0x510)
    #5 0x80001c53 in callMain a.out.js:7251:13
    #6 0x80001c79 in doRun a.out.js:7289:21
    #7 0x80001c85 in run a.out.js:7301:3

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x22f62 in operator new(unsigned long)+0x22f62 (a.out.wasm+0x22f62)
    #1 0x8d97 in std::__2::__thread_struct::__thread_struct()+0x8d97 (a.out.wasm+0x8d97)
    #2 0x17ef in std::__2::thread::thread<main::$_0, void>(main::$_0&&) ../emsdk/upstream/emscripten/system/include/libcxx/thread:294:22
    #3 0x1630 in __original_main main-thread.cc:3:3
    #4 0x3b5d in main+0x3b5d (a.out.wasm+0x3b5d)
    #5 0x80000510  (JavaScript+0x510)
    #6 0x80001c53 in callMain a.out.js:7251:13
    #7 0x80001c79 in doRun a.out.js:7289:21

Indirect leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x22f62 in operator new(unsigned long)+0x22f62 (a.out.wasm+0x22f62)
    #1 0x17e8 in std::__2::thread::thread<main::$_0, void>(main::$_0&&) ../emsdk/upstream/emscripten/system/include/libcxx/thread:294:18
    #2 0x1630 in __original_main main-thread.cc:3:3
    #3 0x3b5d in main+0x3b5d (a.out.wasm+0x3b5d)
    #4 0x80000510  (JavaScript+0x510)
    #5 0x80001c53 in callMain a.out.js:7251:13
    #6 0x80001c79 in doRun a.out.js:7289:21
    #7 0x80001c85 in run a.out.js:7301:3

SUMMARY: AddressSanitizer: 32 byte(s) leaked in 3 allocation(s).

[emaxx-google]

Can't reproduce this on 2.0.16 anymore, so presumably this got fixed in the meantime (maybe by the same fix as #12985).