poll返回有数据可读但是读不出数据于是程序陷入死循环

flynetcn

recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0
poll([{fd=8, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 0) = 1 ([{fd=8, revents=POLLIN}])
recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0
poll([{fd=8, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 0) = 1 ([{fd=8, revents=POLLIN}])
recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0
poll([{fd=8, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 0) = 1 ([{fd=8, revents=POLLIN}])
recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0
poll([{fd=8, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 0) = 1 ([{fd=8, revents=POLLIN}])
recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0
poll([{fd=8, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 0) = 1 ([{fd=8, revents=POLLIN}])
recvfrom(8, "", 1, MSG_PEEK, NULL, NULL) = 0
select(9, [8], [], [], {5, 0})          = 1 (in [8], left {4, 999998})
recvfrom(8, "", 4, 0, NULL, NULL)       = 0

hnwyllmm

If no messages are available to be received and the peer has performed an orderly shutdown, recvfrom() shall return 0.
recvfrom 返回0是这个解释

flynetcn

回复 2# hnwyllmm

谢谢，可能是第二种情况，访问量多，半开连接多，断开连接的时间长。