The -f output with more context(returning to the main thread 30617 and
waiting for another socket connection):
[pid 30670] clock_gettime(CLOCK_REALTIME, {1526142534, 664590192}) = 0
[pid 30670] write(2, "2018/05/13 00:28:54 cmd params c"...,
1492018/05/13 00:28:54 cmd params create -f qcow2
/data/kvm_img/b628579d-ae3d-41f0-887e-895204190c70/new-disk1.qcow2
1024M
) = 149
[pid 30670] stat("/usr/local/sbin/qemu-img", 0xc42005a6b8) = -1 ENOENT
(No such file or directory)
[pid 30670] stat("/usr/local/bin/qemu-img", 0xc42005a788) = -1 ENOENT
(No such file or directory)[pid 30670] stat("/usr/sbin/qemu-img",
0xc42005a858) = -1 ENOENT (No such file or directory)
[pid 30670] stat("/usr/bin/qemu-img", {st_mode=S_IFREG|0755,
st_size=815784, ...}) = 0
[pid 30670] openat(AT_FDCWD, "/dev/null", O_RDONLY|O_CLOEXEC) = 7
[pid 30670] pipe2([8, 9], O_CLOEXEC) = 0
[pid 30670] pipe2([10, 11], O_CLOEXEC) = 0
[pid 30670] close(7) = 0
[pid 30670] close(9) = 0
[pid 30670] close(11) = 0
[pid 30670] close(8) = 0
[pid 30670] close(10) = 0
[pid 30670] write(1, "ret {\"status\":\"error\",\"error\":\"f"...,
79ret {"status":"error","error":"fork/exec /usr/bin/qemu-img: invalid
argument"}
) = 79
[pid 30670] write(6, "{\"status\":\"error\",\"error\":\"fork/"..., 74) = 74
[pid 30670] write(1, "handle over, byebye\n", 20handle over, byebye
) = 20
[pid 30670] epoll_ctl(5, EPOLL_CTL_DEL, 6, 0xc42004ddec) = 0[pid
30670] close(6) = 0
[pid 30670] epoll_wait(5, [], 128, 0) = 0
[pid 30670] epoll_wait(5, <unfinished ...>
[pid 30671] <... sched_yield resumed> ) = 0
[pid 30671] futex(0x9fe610, FUTEX_WAKE, 1) = 0
[pid 30671] clock_gettime(CLOCK_MONOTONIC, {4411908, 247223972}) = 0
[pid 30671] clock_gettime(CLOCK_REALTIME, {1526142534, 671270292}) = 0
[pid 30671] pselect6(0, NULL, NULL, NULL, {0, 20000}, NULL) = 0 (Timeout)
[pid 30671] clock_gettime(CLOCK_MONOTONIC, {4411908, 247815618}) = 0
[pid 30671] futex(0x9fe6d8, FUTEX_WAIT, 0, {60, 0}
Still seems no fork though...
On 13 May 2018 at 00:13, Ian Lance Taylor <i...@golang.org> wrote:
> On Fri, May 11, 2018 at 9:47 PM, Zhang Qiang <dotslash...@gmail.com> wrote:
>>
>> Thanks for your valuable advice on debugging.
>>
>> The SysProcAttr field is nil, and I can't see why it fails from the
>> strace, seems it just found the executable and then fails without
>> doing fork:
>>
>> stat("/usr/bin/qemu-img", {st_mode=S_IFREG|0755, st_size=815784, ...}) = 0
>> write(1, "SysProcAttr: <nil>", 18SysProcAttr: <nil>) = 18
>> openat(AT_FDCWD, "/dev/null", O_RDONLY|O_CLOEXEC) = 7
>> pipe2([8, 9], O_CLOEXEC) = 0
>> pipe2([10, 11], O_CLOEXEC) = 0
>> close(7) = 0
>> close(9) = 0
>> close(11) = 0
>> close(8) = 0
>> close(10) = 0
>> write(1, "ret {\"status\":\"error\",\"error\":\"f"..., 79ret
>> {"status":"error","error":"fork/exec /usr/bin/qemu-img: invalid
>> argument"}
>
> Thanks. That looks like the output from strace, not strace -f.
>
> Ian
>
>
>
>> On 12 May 2018 at 12:30, Ian Lance Taylor <i...@golang.org> wrote:
>>> On Fri, May 11, 2018 at 8:36 PM, Tashi Lu <dotslash...@gmail.com> wrote:
>>>>
>>>> I faced a strange problem： os/exec always fails with `fork/exec
>>>> /usr/bin/qemu-img: invalid argument'.
>>>>
>>>> Simplified code is at https://play.golang.org/p/v1APfzmS2p9. It seems this
>>>> simplified snippet runs well without errors, but my real code is no more
>>>> than just some variable initializations than this snippet. So I suspect
>>>> it's
>>>> the context's problem, but my context is too complex to simplify and put
>>>> onto the playground. What I can think of that what might be linked to this
>>>> error is that this function is run in a goroutine. But I did write a
>>>> simplified goroutine version, sadly it worked well too... I had no idea how
>>>> to do further debugging.
>>>>
>>>> And further, the executable is not to blame, it fails with the same error
>>>> even if I substitute the executable to `ls' or anything else.
>>>>
>>>> Can you provide me some suggestions to the possible reason or the way to
>>>> debug? Thanks.
>>>
>>> I would look first at the SysProcAttr field. Do you set that? Look
>>> closely at the values.
>>>
>>> If that doesn't help, run your failing program under strace -f and
>>> look for the failing system call.
>>>
>>> Ian
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