Sometimes we must spawn a new thread, to avoid the risk of deadlock.
Ensure we always spawn a thread in those cases. In particular this
includes the fillthread.
64 is too low (it's actually reachable), and every sensible system should have a limit above
this.
On OpenBSD and FreeBSD it's ULONG_MAX, on my linux system it's 61990.
Plus we currently fail by hanging if our limit is reached, so this
should improve things regardless.
On my linux system _POSIX_THREAD_THREADS_MAX works out to 64 here,
which is just too low, even tho the system can handle more.
Fixes#6503 harder.
This reintroduces commits 22230a1a0ddddc62732418773f3741073988df96
and 9d7d70c204073fb7fcfc393b8b78821b905e6817, now with the bug fixed.
The problem was when there was one thread waiting in the pool. We enqueue
an item onto the pool and attempt to wake up the thread. But before the
thread runs, we enqueue another item - this second enqueue will see the
thread waiting and attempt to wake it up as well. If the two work items
were dependent (reader/writer) then we would have a deadlock.
The fix is to check if the number of waiting threads is at least as large
as the queue. If the number of enqueued items exceeds the number of waiting
threads, then spawn a new thread always.
This reverts commit 22230a1a0ddddc62732418773f3741073988df96.
Also 9d7d70c204073fb7fcfc393b8b78821b905e6817
There's some subtle bug here, needs to be tracked down and tested.
Improve the iothread behavior by enabling an iothread to stick around for
a while waiting for work. This reduces the amount of iothread churn, which
is useful on platforms where threads are expensive.
Also do other modernization like clean up the locking discipline and use
FLOG.
This runs build_tools/style.fish, which runs clang-format on C++, fish_indent on fish and (new) black on python.
If anything is wrong with the formatting, we should fix the tools, but automated formatting is worth it.
@ridiculousfish had introduced this in 3a45cad12ea392bbc5fe38010d1cdf4a90ba7adb
to work around an issue with Coverity Scan where it couldn't tell the
mutex was correctly locked, but even with the `fish_mutex_t` hack, it
still emits the same warnings, so there's no pointing in keeping it.
Add a fish-specific wrapper around std::mutex that records whether it is
locked in a bool. This is to make ASSERT_IS_LOCKED() simpler (it can just
check the boolean instead of relying on try_lock) which will make Coverity
Scan happier.
Some details: Coverity Scan was complaining about an apparent double-unlock
because it's unaware of the semantics of try_lock(). Specifically fish
asserts that a lock is locked by asserting that try_lock fails; if it
succeeds fish prints an error and then unlocks the lock (so as not to leave
it locked). This unlock is of course correct, but it confused Coverity Scan.
No longer using RAII wrappers around pthread_mutex_t and pthread_cond_t
in favor of the C++11 std::mutex, std::recursive_mutex, and
std::condition_variable data types.
I recently upgraded the software on my macOS server and was dismayed to
see that cppcheck reported a huge number of format string errors due to
mismatches between the format string and its arguments from calls to
`assert()`. It turns out they are due to the macOS header using `%lu`
for the line number which is obviously wrong since it is using the C
preprocessor `__LINE__` symbol which evaluates to a signed int.
I also noticed that the macOS implementation writes to stdout, rather
than stderr. It also uses `printf()` which can be a problem on some
platforms if the stream is already in wide mode which is the normal case
for fish.
So implement our own `assert()` implementation. This also eliminates
double-negative warnings that we get from some of our calls to
`assert()` on some platforms by oclint.
Also reimplement the `DIE()` macro in terms of our internal
implementation.
Rewrite `assert(0 && msg)` statements to `DIE(msg)` for clarity and to
eliminate oclint warnings about constant expressions.
Fixes#3276, albeit not in the fashion I originally envisioned.
Allows iothread_perform to work with void return types on both
g++ and clang
This reverts commit 1040b255c72571581a7de283d7f49c4633c851b4
and reintroduces ac9a0f0dbfeb8b76207202dcda2032faff6ad541
