zenoh-cpp
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eclipse-zenoh
Drop in either `atexit` or `std::signal` causes core dumped.
Description
This issue occurs when a user tries to drop a zenoh entity in atexit or std::signal. This is also the case in rmw_zenoh_cpp. To resolve this issue, we might need to add a compilation flag to turn off the z_drop in the destructor.
To reproduce
- Apply the following patch
diff --git a/examples/universal/z_sub.cxx b/examples/universal/z_sub.cxx
index a53ae23..bf7a4e8 100644
--- a/examples/universal/z_sub.cxx
+++ b/examples/universal/z_sub.cxx
@@ -14,15 +14,27 @@
#include <stdio.h>
#include <chrono>
+#include <csignal>
+#include <cstdlib>
#include <iostream>
+#include <optional>
#include <thread>
#include "../getargs.h"
#include "zenoh.hxx"
+#include "zenoh/api/session.hxx"
+#include "zenoh/api/subscriber.hxx"
using namespace zenoh;
using namespace std::chrono_literals;
+typedef struct Context {
+ std::optional<Session> sess;
+ std::optional<Subscriber<void>> sub;
+} Context;
+
+static Context context;
+
const char *kind_to_str(SampleKind kind) {
switch (kind) {
case SampleKind::Z_SAMPLE_KIND_PUT:
@@ -40,6 +52,14 @@ void data_handler(const Sample &sample) {
<< "')\n";
}
+void handle_sigint(int signal) {
+ if (signal == SIGINT) {
+ std::cout << "Received SIGINT signal. Performing cleanup tasks..." << std::endl;
+ context.sub.reset();
+ exit(0);
+ }
+}
+
int _main(int argc, char **argv) {
const char *expr = "demo/example/**";
const char *locator = nullptr;
@@ -79,14 +99,17 @@ int _main(int argc, char **argv) {
KeyExpr keyexpr(expr);
std::cout << "Opening session..." << std::endl;
- auto session = Session::open(std::move(config));
+ context.sess = Session::open(std::move(config));
std::cout << "Declaring Subscriber on '" << keyexpr.as_string_view() << "'..." << std::endl;
- auto subscriber = session.declare_subscriber(keyexpr, &data_handler, closures::none);
+ context.sub = context.sess.value().declare_subscriber(keyexpr, &data_handler, closures::none);
#ifdef ZENOHCXX_ZENOHC
- std::cout << "Subscriber on '" << subscriber.get_keyexpr().as_string_view() << "' declared" << std::endl;
+ std::cout << "Subscriber on '" << context.sub.value().get_keyexpr().as_string_view() << "' declared" << std::endl;
#endif
+ // Register the signal handler for SIGTERM
+ std::signal(SIGINT, handle_sigint);
+
std::cout << "Press CTRL-C to quit...\n";
while (true) {
std::this_thread::sleep_for(1s);
- Build and run z_sub. And then press Ctrl-C to stop the program.
Error log
➜ ./build/examples/zenohc/z_sub
Opening session...
2024-09-03T06:58:51.977472Z INFO ThreadId(02) zenoh::net::runtime: Using ZID: 41ae6c14329a3f858ac7e4d7843933d3
2024-09-03T06:58:51.978257Z INFO ThreadId(02) zenoh::net::runtime::orchestrator: Zenoh can be reached at: tcp/[fe80::694a:ae45:bf2b:33a0]:33921
2024-09-03T06:58:51.978277Z INFO ThreadId(02) zenoh::net::runtime::orchestrator: Zenoh can be reached at: tcp/192.168.1.140:33921
2024-09-03T06:58:51.978458Z INFO ThreadId(02) zenoh::net::runtime::orchestrator: zenohd listening scout messages on 224.0.0.224:7446
Declaring Subscriber on 'demo/example/**'...
Subscriber on 'demo/example/**' declared
Press CTRL-C to quit...
^CReceived SIGINT signal. Performing cleanup tasks...
thread '<unnamed>' panicked at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/thread/local.rs:246:26:
cannot access a Thread Local Storage value during or after destruction: AccessError
stack backtrace:
0: 0x7983211079fc - std::backtrace_rs::backtrace::libunwind::trace::ha637c64ce894333a
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
1: 0x7983211079fc - std::backtrace_rs::backtrace::trace_unsynchronized::h47f62dea28e0c88d
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
2: 0x7983211079fc - std::sys_common::backtrace::_print_fmt::h9eef0abe20ede486
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:67:5
3: 0x7983211079fc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hed7f999df88cc644
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:44:22
4: 0x798320e95710 - core::fmt::rt::Argument::fmt::h1539a9308b8d058d
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/fmt/rt.rs:142:9
5: 0x798320e95710 - core::fmt::write::h3a39390d8560d9c9
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/fmt/mod.rs:1120:17
6: 0x7983210d4ce2 - std::io::Write::write_fmt::h5fc9997dfe05f882
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/io/mod.rs:1762:15
7: 0x7983211095ae - std::sys_common::backtrace::_print::h894006fb5c6f3d45
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:47:5
8: 0x7983211095ae - std::sys_common::backtrace::print::h23a2d212c6fff936
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:34:9
9: 0x798321108d20 - std::panicking::default_hook::{{closure}}::h8a1d2ee00185001a
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:272:22
10: 0x798321109f08 - std::panicking::default_hook::h6038f2eba384e475
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:292:9
11: 0x798321109f08 - std::panicking::rust_panic_with_hook::h2b5517d590cab22e
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:779:13
12: 0x79832110990c - std::panicking::begin_panic_handler::{{closure}}::h233112c06e0ef43e
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:657:13
13: 0x798321109866 - std::sys_common::backtrace::__rust_end_short_backtrace::h6e893f24d7ebbff8
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:170:18
14: 0x798321109851 - rust_begin_unwind
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:645:5
15: 0x798320cd9044 - core::panicking::panic_fmt::hbf0e066aabfa482c
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:72:14
16: 0x798320cd95b2 - core::result::unwrap_failed::hddb4fea594200c52
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/result.rs:1653:5
17: 0x798321184a67 - zenoh_runtime::ZRuntime::block_in_place::hf9959efffc8868ff
18: 0x7983211c4763 - <zenoh::api::session::Session as core::ops::drop::Drop>::drop::h0e1d6bad44ae52c6
19: 0x798320d4cbfc - core::ptr::drop_in_place<zenoh::api::session::Session>::h3d19805dd420053d
20: 0x798320d55a4d - alloc::sync::Arc<T,A>::drop_slow::h32dc1c11ecc8f032
21: 0x5f7945fcc4e2 - _Z6z_dropP17z_moved_session_t
at /home/user/workspace/src/zenoh-cpp/local/include/zenoh_macros.h:584:62
22: 0x5f7945fcedd8 - _ZN5zenoh5OwnedI17z_owned_session_tED2Ev
at /home/user/workspace/src/zenoh-cpp/include/zenoh/api/base.hxx:81:24
23: 0x5f7945fcd8e0 - _ZN5zenoh7SessionD2Ev
at /home/user/workspace/src/zenoh-cpp/include/zenoh/api/session.hxx:43:7
24: 0x5f7945fd16d4 - _ZNSt22_Optional_payload_baseIN5zenoh7SessionEE10_M_destroyEv
at /usr/include/c++/14.2.1/optional:283:35
25: 0x5f7945fd0944 - _ZNSt22_Optional_payload_baseIN5zenoh7SessionEE8_M_resetEv
at /usr/include/c++/14.2.1/optional:314:14
26: 0x5f7945fcee64 - _ZNSt17_Optional_payloadIN5zenoh7SessionELb0ELb0ELb0EED2Ev
at /usr/include/c++/14.2.1/optional:437:65
27: 0x5f7945fcd9bc - _ZNSt14_Optional_baseIN5zenoh7SessionELb0ELb0EED2Ev
at /usr/include/c++/14.2.1/optional:508:12
28: 0x5f7945fcd9d8 - _ZNSt8optionalIN5zenoh7SessionEED2Ev
at /usr/include/c++/14.2.1/optional:703:11
29: 0x5f7945fd342c - _ZN7ContextD2Ev
at /home/user/workspace/src/zenoh-cpp/examples/universal/z_sub.cxx:31:16
30: 0x79832064e891 - <unknown>
31: 0x79832064e95e - exit
32: 0x5f7945fca947 - _Z13handle_siginti
at /home/user/workspace/src/zenoh-cpp/examples/universal/z_sub.cxx:64:13
33: 0x79832064c1d0 - <unknown>
34: 0x7983206f0733 - clock_nanosleep
35: 0x7983206fc827 - nanosleep
36: 0x5f7945fcfaa3 - _ZNSt11this_thread9sleep_forIlSt5ratioILl1ELl1EEEEvRKNSt6chrono8durationIT_T0_EE
at /usr/include/c++/14.2.1/bits/this_thread_sleep.h:80:20
37: 0x5f7945fcb12f - _Z5_mainiPPc
at /home/user/workspace/src/zenoh-cpp/examples/universal/z_sub.cxx:120:36
38: 0x5f7945fcb3ac - main
at /home/user/workspace/src/zenoh-cpp/examples/universal/z_sub.cxx:128:14
39: 0x798320634e08 - <unknown>
40: 0x798320634ecc - __libc_start_main
41: 0x5f7945fca645 - _start
42: 0x0 - <unknown>
Error: nu::shell::coredump_error
System Info
- zenoh-cpp: 2c5113be33a2b654b26f60393abd38673e0dbe6c
~~Maybe instead of atexit, we could use a static variable that will call all drop logic in its destructor, at least this guaranteed by C++ standard to work correctly.~~ No apparently it is the same as calling function registered with atexit.
There are some (a lot of) system APIs that should not be called in signal handlers, so it is really a bad idea to drop big objects in signal handlers. Moreover, signal handler can be executed concurrently, so thread safety also comes into place. We need to handle signals in a safe way, I can take this task
There are some (a lot of) system APIs that should not be called in signal handlers, so it is really a bad idea to drop big objects in signal handlers. Moreover, signal handler can be executed concurrently, so thread safety also comes into place. We need to handle signals in a safe way, I can take this task
Yes. I agree with your point. Dropping objects within signal handlers isn't a good pattern. Rust has put much effort into addressing this safely within the normal scope.