So I'm swinging back towards this being some kind of platform bug rather
than a gccgo thing. The hung process has three threads each using 100%
of a cpu in system time. strace shows that they are all in futex, this
sort of thing:
(t-doko)ubuntu@arm64:~$ LD_LIBRARY_PATH=/build/buildd/gcc-4.8-4.8.2/lib64
strace -e futex -f ./whut6-arm64-4.9
futex(0x7f906ea21c, FUTEX_WAKE_PRIVATE, 2147483647) = 0
Process 2707 attached
fetching for 0 th time...
[pid 2706] futex(0x7f912c50a0, FUTEX_WAIT, 0, NULLProcess 2708 attached
Process 2709 attached
<unfinished ...>
[pid 2708] futex(0x8d26fd8, FUTEX_WAIT, 0, {60, 0}sending 0
<unfinished ...>
[pid 2709] futex(0x7f912c50a0, FUTEX_WAKE, 1) = 1
[pid 2706] <... futex resumed> ) = 0
[pid 2709] futex(0x8f48088, FUTEX_WAIT, 0, NULLgot 0
fetching for 1 th time...
<unfinished ...>
[pid 2706] futex(0x8f48088, FUTEX_WAKE, 1 <unfinished ...>
It seems to me that the last futex call by 2706 should have woken the
previous one by 2709 but I don' treally know how this works...
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https://bugs.launchpad.net/bugs/1256246
Title:
gccgo/arm64: using channels before main starts is unreliable
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