I'm syncing a rather big list of small files using rsync. My client is rsync 3.0.7-1ubuntu1 running on Ubuntu Lucid, and the server is a backport for rsync 3.0.0-1 for Debian Etch (although I had the same problem with rsync 2.6.9 as server, so it seems to be a problem on the client side).

Some time in the middle of the sync, the client freezes. When I kill it (using ctrl+C or kill), the client returns with an error "undefined error" but the process keeps running in state D (as seen in ps), so it cannot be killed. The servers returns, too, and is not seen anymore in the process list.

Here are the last lines of the strace tracks on both the client and the server:

client:
=================
lstat("archives/private/sun-exploit-build/2009-August/date.html", 0x7fff4c604ec0) = -1 ENOENT (No such file or directory)
lstat("archives/private/sun-exploit-build/2009-August/index.html", {st_mode=S_IFLNK|0777, st_size=11, ...}) = 0
lstat("archives/private/sun-exploit-build/2009-August/subject.html", 0x7fff4c604ec0) = -1 ENOENT (No such file or directory)
lstat("archives/private/sun-exploit-build/2009-August/thread.html", 0x7fff4c604ec0) = -1 ENOENT (No such file or directory)
select(5, [3], [4], [4], {60, 0}) = 1 (out [4], left {59, 999997})
write(4, "\37\3\0\7\0\1\0\240\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\0\240\0\0\0\0\0"..., 803) = 803
gettimeofday({1274270586, 245243}, NULL) = 0
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}) = 0 (Timeout)
select(4, [3], [], NULL, {60, 0}^C <unfinished ...>
=================

server:
=================
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\374\17\0\7", 4) = 4
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\"> (Priorit&eacute; supervision:"..., 4092) = 4092
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\374\17\0\7", 4) = 4
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "AHx8fA6H3JUKXLFmiAGzelQDAw527\nAl"..., 4092) = 4092
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\374\17\0\7", 4) = 4
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "itOSosZqrN5to9mRnA\nOGBL3x59BrQUd"..., 4092) = 4092
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\374\17\0\7", 4) = 4
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "eric@lists.sourceforge.x-echo.co"..., 4092) = 4092
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {60, 0})
write(1, "\374\17\0\7", 4) = 4
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 0 (Timeout)
select(2, NULL, [1], [1], {60, 0}) = 1 (out [1], left {51, 216000})
write(1, ".131.30])\n\tby gwprod01m1.infra.m"..., 4092) = -1 EPIPE (Broken pipe)
--- SIGPIPE (Broken pipe) @ 0 (0) ---
write(2, "rsync: writefd_unbuffered failed"..., 79) = -1 EPIPE (Broken pipe)
--- SIGPIPE (Broken pipe) @ 0 (0) ---
rt_sigaction(SIGUSR1, {SIG_IGN}, NULL, 8) = 0
rt_sigaction(SIGUSR2, {SIG_IGN}, NULL, 8) = 0
write(2, "rsync error: errors with program"..., 83) = -1 EPIPE (Broken pipe)
--- SIGPIPE (Broken pipe) @ 0 (0) ---
rt_sigaction(SIGUSR1, {SIG_IGN}, NULL, 8) = 0
rt_sigaction(SIGUSR2, {SIG_IGN}, NULL, 8) = 0
gettimeofday({1274271146, 160025}, NULL) = 0
select(0, NULL, NULL, NULL, {0, 100000}) = 0 (Timeout)
gettimeofday({1274271146, 259470}, NULL) = 0
select(0, NULL, NULL, NULL, {0, 1000}) = 0 (Timeout)
gettimeofday({1274271146, 263457}, NULL) = 0
exit_group(13) = ?
Process 20281 detached
=================

I can't find where this problem comes from, but I get it every time I relaunch rsync.