InotifyBackend hungs forever when inotify_init1 returns error

[amierzwicki]

Scenario

Sytem: linux (ubuntu 22.04)

When there are too many open inotify instances the parcel build will hung without any clue to why it's stuck.

Expected behavior

Parcel should throw clear exception - e.g. "There are too many open files, cannot initialize inotify instance"

Stretch goal

Suggest to user what are possible actions to fix it (e.g. writing higher value to /proc/sys/fs/inotify/max_user_instances).

Current behavior

When there are too many open inotify instances the inotify_init1 returns -1 with errno "Too many open files". This causes exception in InotifyBackend: https://github.com/parcel-bundler/watcher/blob/master/src/linux/InotifyBackend.cc#L25.

When this happens the Backend::run will block forever due to insufficient error handling (https://github.com/parcel-bundler/watcher/blob/master/src/Backend.cc#L103):

The fix will require a bit more than just calling mStartedSignal.notify() (error needs to be populated up the stack) - the above just highlights in what state the process ends up when this error happens.

Steps to reproduce

1. Setup simple parcel project (package.json + src/index.js is sufficient)
2. Set /proc/sys/fs/inotify/max_user_instances to some small value (e.g. 1)
3. Run parcel build
4. Parcel will hung forever:

> my-library@1.0.0 build
> parcel build

Workaround

Naturally the problem of too many inotify instances needs to be fixed (even when this bug will be resolved) - either by closing old processes in system or by increasing the limit echo 256 | sudo tee /proc/sys/fs/inotify/max_user_instances (default is often 128).

[jsimomaa]

(Just as FYI for possible crawlers with the same problem than I had)

I encountered this bug as well during a gatsby build:

gatsby build --verbose
verbose 0.537943215 set gatsby_log_level: "verbose"
verbose 0.53914066 set gatsby_executing_command: "build"
verbose 0.539580282 loading local command from: /usr/src/app/node_modules/gatsby/dist/commands/build.js
verbose 1.741638654 running command: build
verbose 1.742558817 Running build in "production" environment

And stuck here forever. GDB helped me to trace the issue here:

(gdb) bt
#0  __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x7fb2546d5fb8) at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common (futex_word=futex_word@entry=0x7fb2546d5fb8, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0, cancel=cancel@entry=true) at ./nptl/futex-internal.c:87
#2  0x00007fb255840e0b in __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x7fb2546d5fb8, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139
#3  0x00007fb255843468 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7fb2546d5f68, cond=0x7fb2546d5f90) at ./nptl/pthread_cond_wait.c:503
#4  ___pthread_cond_wait (cond=0x7fb2546d5f90, mutex=0x7fb2546d5f68) at ./nptl/pthread_cond_wait.c:618
#5  0x00007fb255b4941d in std::condition_variable::wait(std::unique_lock<std::mutex>&) () from /lib/x86_64-linux-gnu/libstdc++.so.6
#6  0x00007fb236c3e13f in Backend::run() () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#7  0x00007fb236c3f0bd in Backend::getShared(std::basic_string<char, std::char_traits<char>, std::allocator<char> >) () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#8  0x00007fb236c3f137 in Backend::getShared(std::basic_string<char, std::char_traits<char>, std::allocator<char> >) () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#9  0x00007fb236c26154 in getBackend(Napi::Env, Napi::Value) () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#10 0x00007fb236c281dd in writeSnapshot(Napi::CallbackInfo const&) () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#11 0x00007fb236c2ccea in Napi::details::CallbackData<Napi::Value (*)(Napi::CallbackInfo const&), Napi::Value>::Wrapper(napi_env__*, napi_callback_info__*) () from /usr/src/app/node_modules/@parcel/watcher-linux-x64-glibc/watcher.node
#12 0x0000000000b35769 in v8impl::(anonymous namespace)::FunctionCallbackWrapper::Invoke(v8::FunctionCallbackInfo<v8::Value> const&) ()
#13 0x0000000000dcd3e0 in v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, v8::internal::BuiltinArguments) ()
#14 0x0000000000dce91f in v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) ()
#15 0x000000000170dfb9 in Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_BuiltinExit ()
#16 0x0000000001691f10 in Builtins_InterpreterEntryTrampoline ()