curl -m not working due to connect call hangs

[tg123]

• Your Windows build number: (Type ver at a Windows Command Prompt)

Microsoft Windows [Version 10.0.15063]

• What you're doing and what's happening: (Copy&paste specific commands and their output, or include screen shots)

curl -m 1 did not end in 1s, but a long time

• What's wrong / what should be happening instead:

seems connect call takes a long time (see strace log)

• Strace of the failing command, if applicable: (If <cmd> is failing, then run strace -o strace.txt -ff <cmd>, and post the strace.txt output here)

strace -T curl 1.2.3.4:5678 -m 1

shows connect cost 21s

socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 4 <0.000104>
setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0 <0.000028>
setsockopt(4, SOL_TCP, TCP_KEEPIDLE, [60], 4) = 0 <0.000019>
setsockopt(4, SOL_TCP, TCP_KEEPINTVL, [60], 4) = 0 <0.000047>
fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR) <0.000025>
fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK)    = 0 <0.000032>
clock_gettime(CLOCK_MONOTONIC, {166492, 668494000}) = 0 <0.000045>
connect(4, {sa_family=AF_INET, sin_port=htons(5678), sin_addr=inet_addr("1.2.3.4")}, 16) = -1 EAGAIN (Resource temporarily unavailable) <21.002000>
clock_gettime(CLOCK_MONOTONIC, {166513, 672789000}) = 0 <0.000054>

vs strace on Ubuntu 16.04.2

socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 4 <0.000024>
setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0 <0.000018>
setsockopt(4, SOL_TCP, TCP_KEEPIDLE, [60], 4) = 0 <0.000012>
setsockopt(4, SOL_TCP, TCP_KEEPINTVL, [60], 4) = 0 <0.000017>
fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR) <0.000010>
fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK)    = 0 <0.000018>
clock_gettime(CLOCK_MONOTONIC, {1282779, 886594029}) = 0 <0.000010>
connect(4, {sa_family=AF_INET, sin_port=htons(5678), sin_addr=inet_addr("1.2.3.4")}, 16) = -1 EINPROGRESS (Operation now in progress) <0.000048>

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[therealkenc]

shows connect cost 21s

21 seconds. Surely the same as #1829 (message) #1584. Non-blocking connect getting popular as a feature request lately (#903).

[sunilmut]

@tg123 - Thanks for your post and the trace. Very helpful.

Yes, non-blocking connect seems to be coming up more frequently now. Note taken. Marking this one as dupe.