我有一个日志应用程序，通过udp接收数据快速写入非压缩文件。然后，当触发某个句点或文件大小时，我们重命名该文件并发出包含以下内容的系统命令：
"(gzip file; mv file.gz xxx;) &"
我在任何地方都使用cloexec，因此不会发生泄漏。 Valgrind没有错误。
问题在于一切都很美妙，但有时它会挂在
中 system("(gzip file; mv file.gz xxx;) &")
我对该程序进行了操作，并使用一些数据运行它，并在wait4中挂起它看起来像
我检查了ps命令，它显示了一个fork创建的pid，所以进程在那里，但显然有些东西被绞死。
下面的strace有一个正常的fork执行系统命令ok，最后一个挂在wait4中。 （介于两者之间有udp读取）
我可以请专家检查一下，看看我做错了什么！
我买啤酒：D
stat("5001", {st_mode=S_IFDIR|0755, st_size=512, ...}) = 0
open("5001", O_RDONLY) = 9
fcntl(9, F_SETFD, FD_CLOEXEC) = 0
getdents(9, /* 2 entries */, 3933) = 32
getdents(9, /* 0 entries */, 3933) = 0
close(9) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
fork() = 3056
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_IGN}, 8) = 0
wait4(3056, [WIFEXITED(s) && WEXITSTATUS(s) == 0], 0, NULL) = 3056
--- SIGCHLD (Child exited) @ 0 (0) ---
rt_sigaction(SIGQUIT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGINT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
open("5001_writable", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 9
ioctl(9, TCGETS, 0xbeffe840) = -1 ENOTTY (Inappropriate ioctl for device)
fcntl(9, F_SETFD, FD_CLOEXEC) = 0
gettimeofday({1444247518, 979354}, NULL) = 0
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:02,907 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 100549}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:02,907 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:02,998 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 200931}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:02,998 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:03,107 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 299373}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:03,107 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:03,257 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 378612}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:03,257 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:03,348 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 456557}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:03,348 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:03,476 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 560522}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:03,476 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:03,587 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 630370}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:03,587 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:04,087 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 710730}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:04,087 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:04,267 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247519, 779748}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:04,267 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [3]) = 0
recvfrom(8, "\342\207\221", 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 3
gettimeofday({1444247519, 853032}, NULL) = 0
close(9) = 0
stat("5001_writable_tmp", 0xbeffe7e4) = -1 ENOENT (No such file or directory)
stat("5001_writable_tmp", 0xbeffe7e4) = -1 ENOENT (No such file or directory)
rename("5001_writable", "5001_writable_tmp") = 0
stat("5001", {st_mode=S_IFDIR|0755, st_size=512, ...}) = 0
open("5001", O_RDONLY) = 9
fcntl(9, F_SETFD, FD_CLOEXEC) = 0
getdents(9, /* 3 entries */, 3933) = 48
stat("5001/1", {st_mode=S_IFREG|0644, st_size=194, ...}) = 0
getdents(9, /* 0 entries */, 3933) = 0
close(9) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
fork() = 3061
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_IGN}, 8) = 0
wait4(3061, [WIFEXITED(s) && WEXITSTATUS(s) == 0], 0, NULL) = 3061
--- SIGCHLD (Child exited) @ 0 (0) ---
rt_sigaction(SIGQUIT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGINT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
open("5001_writable", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 9
ioctl(9, TCGETS, 0xbeffe840) = -1 ENOTTY (Inappropriate ioctl for device)
fcntl(9, F_SETFD, FD_CLOEXEC) = 0
gettimeofday({1444247520, 154962}, NULL) = 0
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [122]) = 0
recvfrom(8, "\0020\00307.10.2015 19:51:04,908 MAIN "..., 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 122
gettimeofday({1444247520, 273288}, NULL) = 0
write(9, "\0020\00307.10.2015 19:51:04,908 MAIN "..., 122) = 122
select(9, [8], NULL, NULL, {30, 0}) = 1 (in [8], left {30, 0})
ioctl(8, FIONREAD, [3]) = 0
recvfrom(8, "\342\207\221", 4096, 0, {sa_family=AF_INET, sin_port=htons(44384), sin_addr=inet_addr("127.0.0.1")}, [16]) = 3
gettimeofday({1444247520, 403675}, NULL) = 0
close(9) = 0
stat("5001_writable_tmp", 0xbeffe7e4) = -1 ENOENT (No such file or directory)
stat("5001_writable_tmp", 0xbeffe7e4) = -1 ENOENT (No such file or directory)
rename("5001_writable", "5001_writable_tmp") = 0
stat("5001", {st_mode=S_IFDIR|0755, st_size=512, ...}) = 0
open("5001", O_RDONLY) = 9
fcntl(9, F_SETFD, FD_CLOEXEC) = 0
getdents(9, /* 4 entries */, 3933) = 64
stat("5001/1", {st_mode=S_IFREG|0644, st_size=194, ...}) = 0
stat("5001/2", {st_mode=S_IFREG|0644, st_size=177, ...}) = 0
getdents(9, /* 0 entries */, 3933) = 0
close(9) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
fork() = 3066
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_IGN}, 8) = 0
wait4(3066,