fix(mge): limit task queue size

GitOrigin-RevId: a25c3390fc9742b48b6617f2d8887b3769aa4160

imperative/src/impl/interpreter/interpreter_impl.h

@@ -157,10 +157,19 @@ private:
         // set max_spin=0 to prevent Queue fetch task in busy wait manner.
         // this won't affect throughput when python interpreter is sending enough task,
         // but will significantly save CPU time when waiting for task, e.g. wait for data input
-        // limit pending tasks to 1000000
+        // limit pending tasks to 10000
         WorkQueue(ChannelImpl* owner)
-                : AsyncQueueSC<IdentifiedCommand, WorkQueue>(0, 1000000), m_owner(owner) {
+                : AsyncQueueSC<IdentifiedCommand, WorkQueue>(0, 10000), m_owner(owner) {
             sys::set_thread_name("interpreter");
+            if (const char* env_val = MGB_GETENV("MEGENGINE_ASYNC_QUEUE_SIZE")) {
+                int len = strlen(env_val);
+                for (int i = 0; i < len; i ++) {
+                    mgb_assert(env_val[i] >= '0' && env_val[i] <= '9', "async queue size should be an integer");
+                }
+                size_t val;
+                sscanf(env_val, "%zu", &val);
+                update_max_items(val);
+            }
         }
         void process_one_task(IdentifiedCommand& icmd) {
             m_owner->process_one_task(icmd);

src/core/include/megbrain/utils/thread_impl_1.h

@@ -264,6 +264,13 @@ namespace mgb {
                 return m_synchronizer.check_finished();
             }
 
+            void update_max_items(ptrdiff_t max_items) {
+                if (max_items >= 0) {
+                    // -1 / 2 == 0
+                    m_block_quota = (max_items - 1) / BLOCK_SIZE + 1;
+                }
+            }
+
         protected:
             ~AsyncQueueSC() noexcept = default;