sudo를 사용하여 사용자를 전환하는 속도가 느립니다(몇 분 정도 소요).

Debian 9(Stretch)를 실행하는 가상 머신이 있습니다.

내 사용자 계정으로 로그인할 수 있습니다.

그러나 Switch User 를 사용하려고 할 때마다 sudo su(즉시) 비밀번호를 입력한 후 성공하는 데 몇 분이 걸립니다. 다른 사용자가 루트인지 다른 사용자 계정인지는 중요하지 않습니다.

sudo예를 들어 다른 명령을 사용하면 sudo echo잘 작동합니다. (호스트 이름 해결과 관련된 문제를 포함하여 일반적으로 느린 sudo 명령을 디버깅하는 단계를 시도했는데 모든 것이 괜찮을 것입니다.)

관련된 다른 프로세스를 확인했지만 sudo아무것도 발견하지 못했습니다.

running 을 시도했고 sudo strace sudo su다음과 같은 출력을 얻었습니다(마지막 몇 줄만 표시됩니다. 다시 프로세스가 성공하는 데 몇 분이 걸렸습니다).

fcntl(8, F_SETLKW, {l_type=F_RDLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0
read(8, "\2\0\0\0\0\0\0\0~\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
read(8, "\6\0\0\0\213\2\0\0ttyS0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
read(8, "\6\0\0\0\214\2\0\0tty1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
read(8, "\1\0\0\0005\0\0\0~\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
read(8, "\7\0\0\0e\32\0\0pts/0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
read(8, "\7\0\0\0TL\0\0pts/1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 384) = 384
fcntl(8, F_SETLKW, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0
alarm(0)                                = 10
rt_sigaction(SIGALRM, {sa_handler=0x55dacfaa8200, sa_mask=~[KILL STOP RTMIN RT_1], sa_flags=SA_RESTORER|SA_INTERRUPT|SA_SIGINFO, sa_restorer=0x7f8ab6d33060}, NULL, 8) = 0
close(8)                                = 0
getuid()                                = 0
socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 8
connect(8, {sa_family=AF_UNIX, sun_path="/dev/log"}, 110) = 0
sendto(8, "<86>Mar  4 00:20:35 sudo: pam_un"..., 95, MSG_NOSIGNAL, NULL, 0) = 95
socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = 9
fcntl(9, F_SETFD, FD_CLOEXEC)           = 0
sendto(9, {{len=120, type=0x451 /* NLMSG_??? */, flags=NLM_F_REQUEST|NLM_F_ACK, seq=3, pid=0}, "op=PAM:session_open acct=\"root\" "...}, 120, 0, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 120
poll([{fd=9, events=POLLIN}], 1, 500)   = 1 ([{fd=9, revents=POLLIN}])
recvfrom(9, {{len=36, type=NLMSG_ERROR, flags=0, seq=3, pid=2859367897}, "\0\0\0\0x\0\0\0Q\4\5\0\3\0\0\0\0\0\0\0"}, 8988, MSG_PEEK|MSG_DONTWAIT, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, [12]) = 36
recvfrom(9, {{len=36, type=NLMSG_ERROR, flags=0, seq=3, pid=2859367897}, "\0\0\0\0x\0\0\0Q\4\5\0\3\0\0\0\0\0\0\0"}, 8988, MSG_DONTWAIT, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, [12]) = 36
close(9)                                = 0
getpgrp()                               = 23062
rt_sigaction(SIGCHLD, {sa_handler=0x55dacfaa8200, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_INTERRUPT|SA_SIGINFO, sa_restorer=0x7f8ab6d33060}, NULL, 8) = 0
rt_sigaction(SIGCONT, {sa_handler=0x55dacfaa8200, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_INTERRUPT|SA_SIGINFO, sa_restorer=0x7f8ab6d33060}, NULL, 8) = 0
rt_sigaction(SIGTSTP, {sa_handler=0x55dacfaa8140, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_INTERRUPT|SA_SIGINFO, sa_restorer=0x7f8ab6d33060}, NULL, 8) = 0
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f8ab7d1ff50) = 23072
close(7)                                = 0
poll([{fd=3, events=POLLIN}, {fd=6, events=POLLIN}], 2, -1) = 1 ([{fd=6, revents=POLLIN|POLLHUP}])
recvfrom(6, "", 8, MSG_WAITALL, NULL, NULL) = 0
poll([{fd=3, events=POLLIN}], 1, -1)    = ? ERESTART_RESTARTBLOCK (Interrupted by signal)
--- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
restart_syscall(<... resuming interrupted poll ...>) = ? ERESTART_RESTARTBLOCK (Interrupted by signal)
--- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
restart_syscall(<... resuming interrupted restart_syscall ...>

poll버퍼를 플러시하는 것처럼 보이지 않기 때문에(불완전한 줄에서 일시 중지됨) 프로세스가 중지되는 줄 restart_syscall을 정확히 말하기는 어렵지만 처음부터 로그 끝에 있는 줄은 프로세스가 지연됩니다.

이 출력을 해석하는 방법을 모르므 strace로 조언이나 팁을 주시면 감사하겠습니다.

내 질문: 이 출력에 따르면 strace사용자를 전환하는 데 왜 그렇게 오랜 시간이 걸립니까 sudo?

---

편집: 댓글에 있는 @Ferenc Wágner의 팁 덕분에 반복해서 반복되는 것처럼 보이는 많은 프로세스를 추가 -f하고 strace발견했습니다 . sudo su아직도 정확히 문제가 무엇인지 잘 모르겠습니다. (아래 로그에서 도메인 이름을 익명화했습니다. 이 IP 주소는 표준 Google Cloud IP라고 생각합니다.)

다음은 출력의 예입니다 sudo strace -f -t sudo su. 출력이 매우 크고 빠르지만, 서로 다른 포크에서 동일한 프로세스를 계속해서 반복하는 것 같습니다.

pid 17113] 17:29:51 poll(NULL, 0, 4strace: Process 20730 attached
 <unfinished ...>
[pid 20730] 17:29:51 set_robust_list(0x7fa609e0a9e0, 24) = 0
[pid 20730] 17:29:51 getpid()           = 17113
[pid 20730] 17:29:51 open("/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 3
[pid 20730] 17:29:51 fstat(3, {st_mode=S_IFREG|0644, st_size=154, ...}) = 0
[pid 20730] 17:29:51 read(3, "domain us-central1-a.c.my-domai"..., 4096) = 154
[pid 20730] 17:29:51 read(3, "", 4096)  = 0
[pid 20730] 17:29:51 close(3)           = 0
[pid 20730] 17:29:51 open("/etc/hosts", O_RDONLY|O_CLOEXEC) = 3
[pid 20730] 17:29:51 fstat(3, {st_mode=S_IFREG|0644, st_size=453, ...}) = 0
[pid 20730] 17:29:51 read(3, "127.0.0.1\tlocalhost my-domain i"..., 4096) = 453
[pid 20730] 17:29:51 read(3, "", 4096)  = 0
[pid 20730] 17:29:51 close(3)           = 0
[pid 20730] 17:29:51 madvise(0x7fa60960a000, 8368128, MADV_DONTNEED) = 0
[pid 20730] 17:29:51 exit(0)            = ?
[pid 20730] 17:29:51 +++ exited with 0 +++
[pid 17113] 17:29:51 <... poll resumed> ) = 0 (Timeout)
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) = 3
[pid 17113] 17:29:51 setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
[pid 17113] 17:29:51 fcntl(3, F_GETFL)  = 0x2 (flags O_RDWR)
[pid 17113] 17:29:51 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
[pid 17113] 17:29:51 connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("169.254.169.254")}, 16) = -1 EINPROGRESS (Operation now in progress)
[pid 17113] 17:29:51 poll([{fd=3, events=POLLOUT|POLLWRNORM}], 1, 0) = 0 (Timeout)
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 poll([{fd=3, events=POLLOUT}], 1, 199) = 1 ([{fd=3, revents=POLLOUT}])
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 poll([{fd=3, events=POLLOUT|POLLWRNORM}], 1, 0) = 1 ([{fd=3, revents=POLLOUT|POLLWRNORM}])
[pid 17113] 17:29:51 getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
[pid 17113] 17:29:51 getpeername(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("169.254.169.254")}, [128->16]) = 0
[pid 17113] 17:29:51 getsockname(3, {sa_family=AF_INET, sin_port=htons(37960), sin_addr=inet_addr("10.128.0.2")}, [128->16]) = 0
[pid 17113] 17:29:51 sendto(3, "GET /computeMetadata/v1/oslogin/"..., 134, MSG_NOSIGNAL, NULL, 0) = 134
[pid 17113] 17:29:51 poll([{fd=3, events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}], 1, 0) = 0 (Timeout)
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 poll([{fd=3, events=POLLIN}], 1, 198) = 1 ([{fd=3, revents=POLLIN}])
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 poll([{fd=3, events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}], 1, 0) = 1 ([{fd=3, revents=POLLIN|POLLRDNORM}])
[pid 17113] 17:29:51 recvfrom(3, "HTTP/1.1 404 Not Found\r\nMetadata"..., 16384, 0, NULL, NULL) = 496
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 close(3)           = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 stat("/var/google-users.d/root", 0x7fff47fdaf50) = -1 ENOENT (No such file or directory)
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 clone(child_stack=0x7fa609e09fb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7fa609e0a9d0, tls=0x7fa609e0a700, child_tidptr=0x7fa609e0a9d0) = 20732
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 rt_sigaction(SIGPIPE, {sa_handler=SIG_IGN, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa611ec0060}, NULL, 8) = 0
[pid 17113] 17:29:51 poll(NULL, 0, 4strace: Process 20732 attached
 <unfinished ...>

따라서 이것은 확실히 네트워크 문제이지만 문제가 무엇인지 잘 모르겠습니다.

파일 /etc/hosts은 다음과 같습니다.

127.0.0.1       localhost my-domain my-domain.site.com
127.0.1.1       localhost my-domain my-domain.site.com # trying to resolve this issue, probably not needed
::1             localhost ip6-localhost ip6-loopback my-domain my-domain.site.com
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters

10.128.0.2 my-domain.us-central1-a.c.my-domain.internal my-domain  # Added by Google
169.254.169.254 metadata.google.internal  # Added by Google

파일 의 내용은 /etc/resolv.conf다음과 같습니다.

domain us-central1-a.c.my-domain.internal
search us-central1-a.c.my-domain.internal. c.my-domain.internal. google.internal.
nameserver 169.254.169.254

이 명령은 다음 hostname을 제공합니다.

my-domain

sudo어느 정도는 다르다는 것을 읽었 지만 여기서(예를 들어) 내가 찾으려고 하는 것이 흥미롭지 않은지 hostname잘 모르겠습니다 .sudo susudo echo