Reland "[d8] Dump stack trace on d8 tests timeouts on posix systems"

This is a reland of commit 5592bad9

Disable timeout signal handler with --fuzzing

Original change's description:
> [d8] Dump stack trace on d8 tests timeouts on posix systems
>
> - Add a SIGTERM handler in d8 that dupms the stack trace
> - Send SIGTERM before SIGKILL in the test runner
>
> Bug: v8:13115
> Change-Id: I75285f33caabab61ff6ae83c1fbc6faf45cf595a
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3791906
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82173}

Bug: v8:13115
Change-Id: I8ddbf2a5e601737c2326384d832902b38c371f81
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3816670Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82296}

src/d8/d8.cc

@@ -70,6 +70,10 @@
 #include "src/utils/utils.h"
 #include "src/web-snapshot/web-snapshot.h"
 
+#if V8_OS_POSIX
+#include <signal.h>
+#endif  // V8_OS_POSIX
+
 #ifdef V8_FUZZILLI
 #include "src/d8/cov.h"
 #endif  // V8_FUZZILLI
@@ -5515,9 +5519,34 @@ bool HasFlagThatRequiresSharedIsolate() {
   return i::FLAG_shared_string_table || i::FLAG_harmony_struct;
 }
 
+#ifdef V8_OS_POSIX
+void d8_sigterm_handler(int signal) {
+  // Dump stacktraces when terminating d8 instances with SIGTERM.
+  // SIGKILL is not intercepted.
+  if (signal == SIGTERM) {
+    FATAL("d8: Received SIGTERM signal (likely due to a TIMEOUT)\n");
+  } else {
+    UNREACHABLE();
+  }
+}
+#endif  // V8_OS_POSIX
+
+void d8_install_sigterm_handler() {
+#ifdef V8_OS_POSIX
+  CHECK(!i::FLAG_fuzzing);
+  struct sigaction sa;
+  sa.sa_handler = d8_sigterm_handler;
+  sigemptyset(&sa.sa_mask);
+  if (sigaction(SIGTERM, &sa, NULL) == -1) {
+    FATAL("Could not install SIGTERM handler");
+  }
+#endif  // V8_OS_POSIX
+}
+
 }  // namespace
 
 int Shell::Main(int argc, char* argv[]) {
+  if (!i::FLAG_fuzzing) d8_install_sigterm_handler();
   v8::base::EnsureConsoleOutput();
   if (!SetOptions(argc, argv)) return 1;
 

tools/testrunner/local/command.py

@@ -200,6 +200,11 @@ class PosixCommand(BaseCommand):
 
   def _kill_process(self, process):
     # Kill the whole process group (PID == GPID after setsid).
+    # First try a soft term to allow some feedback
+    os.killpg(process.pid, signal.SIGTERM)
+    # Give the process some time to cleanly terminate.
+    time.sleep(0.1)
+    # Forcefully kill processes.
     os.killpg(process.pid, signal.SIGKILL)