Fix OOM handling on a background thread.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 256 matching lines @@
 void i::FatalProcessOutOfMemory(const char* location) {
   i::V8::FatalProcessOutOfMemory(location, false);
 }
 
 // When V8 cannot allocate memory FatalProcessOutOfMemory is called. The default
 // OOM error handler is called and execution is stopped.
 void i::V8::FatalProcessOutOfMemory(const char* location, bool is_heap_oom) {
   i::Isolate* isolate = i::Isolate::Current();
   char last_few_messages[Heap::kTraceRingBufferSize + 1];
   char js_stacktrace[Heap::kStacktraceBufferSize + 1];
+  i::HeapStats heap_stats;
+
+  if (isolate == nullptr) {
+    // On a background thread -> we cannot retrieve memory information from the
+    // Isolate. Write easy-to-recognize values on the stack.
+    memset(last_few_messages, 0x0badc0de, Heap::kTraceRingBufferSize + 1);
+    memset(js_stacktrace, 0x0badc0de, Heap::kStacktraceBufferSize + 1);
+    memset(&heap_stats, 0xbadc0de, sizeof(heap_stats));
+    // Note that the embedder's oom handler won't be called in this case. We
+    // just crash.
+    FATAL("API fatal error handler returned after process out of memory");
+    return;
+  }
+
   memset(last_few_messages, 0, Heap::kTraceRingBufferSize + 1);
   memset(js_stacktrace, 0, Heap::kStacktraceBufferSize + 1);
 
-  i::HeapStats heap_stats;
   intptr_t start_marker;
   heap_stats.start_marker = &start_marker;
   size_t new_space_size;
   heap_stats.new_space_size = &new_space_size;
   size_t new_space_capacity;
   heap_stats.new_space_capacity = &new_space_capacity;
   size_t old_space_size;
   heap_stats.old_space_size = &old_space_size;
   size_t old_space_capacity;
   heap_stats.old_space_capacity = &old_space_capacity;
@@ skipping 9124 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8