After the commit 7f3c22532577, writing to pipe extremely slows down. This is because cygwait(select_sem, 10, cw_cancel) is called even when write operation is already completed. With this patch, the cygwait() is called only if the write operation is not completed.
Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256398.html Fixes: 7f3c22532577 ("Cygwin: pipe: handle signals explicitely in raw_write") Reported-by: Jim Reisert AD1C <jjreis...@alum.mit.edu> Reviewed-by: Signed-off-by: Takashi Yano <takashi.y...@nifty.ne.jp> --- winsup/cygwin/fhandler/pipe.cc | 6 ++++-- winsup/cygwin/release/3.5.5 | 3 +++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/winsup/cygwin/fhandler/pipe.cc b/winsup/cygwin/fhandler/pipe.cc index 852076ccc..c686df650 100644 --- a/winsup/cygwin/fhandler/pipe.cc +++ b/winsup/cygwin/fhandler/pipe.cc @@ -518,8 +518,9 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len) raise (SIGPIPE); goto out; } - else - cygwait (select_sem, 10, cw_cancel); + /* Break out on completion */ + if (waitret == WAIT_OBJECT_0) + break; /* If we got a timeout in the blocking case, and we already did a short write, we got a signal in the previous loop. */ if (waitret == WAIT_TIMEOUT && short_write_once) @@ -527,6 +528,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len) waitret = WAIT_SIGNALED; break; } + cygwait (select_sem, 10, cw_cancel); } /* Loop in case of blocking write or SA_RESTART */ while (waitret == WAIT_TIMEOUT || waitret == WAIT_SIGNALED); diff --git a/winsup/cygwin/release/3.5.5 b/winsup/cygwin/release/3.5.5 index a98687c26..904119a38 100644 --- a/winsup/cygwin/release/3.5.5 +++ b/winsup/cygwin/release/3.5.5 @@ -4,3 +4,6 @@ Fixes: - Fix undesired behaviour of console master thread in win32-input-mode which is supported by Windows Termainal. Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256380.html + +- Fix a regression in 3.5.4 that writing to pipe extremely slows down. + Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256398.html -- 2.45.1
