Small simplification and generalization of the issue:
The location of the directory and the file in relation to each other
is irrelevant. I can still reproduce the issue with the directory
being on one drive and the file on another. The flock error ("Bad
addr") didn't happen in some variations (e.g. directory on C drive and
file on D drive), but given how rare the error is to begin with, I
assume it's only a timing issue (my D drive is older than my C for
instance)On Tue, Oct 21, 2025 at 5:41 PM Nahor <[email protected]> wrote: > > Hi, > > There is a test in the Fish shell (tests::history::test_history_races) > that systematically fails when I run it. The test simulates multiple > processes/threads trying to write to the shell history file at the > same time. > In my case, the test freezes/deadlocks with errors like "Bad Addr" and > "Is Directory". > When I add a sleep, the freeze/deadlocks disappear but the test > eventually fails because the fake history is not the right size. > See https://github.com/fish-shell/fish-shell/issues/11933 for more details. > > I wrote a test case in pure C (attached) that also triggers the issue > although it's not as systematic (30-50%). > To compile: gcc main.c -o test.exe > To run: ./test.exe > > > Most failures look like this: > ``` > $ ./test.exe > tmp_dir: /tmp/flockc2Hz4c > open file error: 21 - Is a directory > /tmp/flockc2Hz4c/append_file > assertion "file_fd >= 0" failed: file "main.c", line 49, function: > thread_func > Aborted > ``` > Occasionally (maybe 10%), it looks like that: > ``` > $ ./test.exe > tmp_dir: /tmp/flock5Oly9J > lock error: 14 - Bad address > assertion "lock_res == 0" failed: file "main.c", line 38, > function: thread_func > Aborted > ``` > > I believe the freeze/deadlock in the Fish test is because, unlike my > test, they don't assert/crash, and the next time they access the > history file, there is a bunch of deadlock in cygwin internals. > If that helps, this is a partial capture of the stack traces at one such time: > ``` > Thread 9 > #2 0x00000001800d487f in muto::acquire (this=0x1802c24c0 > <lock_process::locker>, ms=ms@entry=4294967295) at > /d/S/B/src/msys2-runtime/winsup/cygwin/sync.cc:84 > #3 0x00000001800dd6e0 in dtable::lock (this=<optimized out>) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/dtable.h:77 > #4 cygheap_fdnew::cygheap_fdnew (this=<synthetic pointer>, > seed_fd=-1, lockit=true) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/cygheap.h:593 > #5 open (unix_path=0xa0002b3b0 > "[...]/fish-shell/target/fish-test-home", flags=262144) at > /d/S/B/src/msys2-runtime/winsup/cygwin/syscalls.cc:1576 > > Thread 10 > #2 0x00000001800d487f in muto::acquire (this=0x1802c24c0 > <lock_process::locker>, ms=ms@entry=4294967295) at > /d/S/B/src/msys2-runtime/winsup/cygwin/sync.cc:84 > #3 0x00000001800dd6e0 in dtable::lock (this=<optimized out>) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/dtable.h:77 > #4 cygheap_fdnew::cygheap_fdnew (this=<synthetic pointer>, > seed_fd=-1, lockit=true) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/cygheap.h:593 > #5 open (unix_path=0xa0002bfe0 > "[...]/fish-shell/target/fish-test-home/race_test_history.FwyAgK", > flags=264706) at > /d/S/B/src/msys2-runtime/winsup/cygwin/syscalls.cc:1576 > > Thread 11 > #2 0x00000001800670bb in inode_t::LOCK (this=0x80000ba20) at > /d/S/B/src/msys2-runtime/winsup/cygwin/flock.cc:314 > #3 inode_t::get (dev=1881899537, ino=ino@entry=10977524092162599, > create_if_missing=create_if_missing@entry=false, lock=lock@entry=true) > at /d/S/B/src/msys2-runtime/winsup/cygwin/flock.cc:504 > #4 0x0000000180068eb1 in fhandler_base::del_my_locks > (this=0x80000b810, from=on_close) at > /d/S/B/src/msys2-runtime/winsup/cygwin/flock.cc:402 > #5 0x000000018010d5bf in fhandler_base::close_with_arch > (this=0x80000b810, flag=flag@entry=-1) at > /d/S/B/src/msys2-runtime/winsup/cygwin/fhandler/base.cc:1306 > #6 0x00000001800de36b in __close (fd=5, flag=-1) at > /d/S/B/src/msys2-runtime/winsup/cygwin/syscalls.cc:1710 > #7 close (fd=5) at > /d/S/B/src/msys2-runtime/winsup/cygwin/syscalls.cc:1722 > > Thread 12 > #2 0x00000001800d487f in muto::acquire (this=0x1802c24c0 > <lock_process::locker>, ms=ms@entry=4294967295) at > /d/S/B/src/msys2-runtime/winsup/cygwin/sync.cc:84 > #3 0x00000001800dd6e0 in dtable::lock (this=<optimized out>) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/dtable.h:77 > #4 cygheap_fdnew::cygheap_fdnew (this=<synthetic pointer>, > seed_fd=-1, lockit=true) at > /d/S/B/src/msys2-runtime/winsup/cygwin/local_includes/cygheap.h:593 > #5 open (unix_path=0x7ff10b488 > "[...]/fish-shell/target/fish-test-home/race_test_history.pZO5DS", > flags=263169) at > /d/S/B/src/msys2-runtime/winsup/cygwin/syscalls.cc:1576 > ``` > The freeze/deadlock can be reproduced in my C code by calling > "continue" inside the "if (lock_res != 0) {" instead of triggering the > assert just after. > > > I haven't been able to reproduce the missing data in the history file > so it's unknown if it's an issue in Fish or flock not locking properly > at times. So far the test passes on Linux and MacOS. > > > Thanks, > Nahor -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
