crashed on sync.cc line 88

[0oneo]

Should this be an issue in the gRPC issue tracker?

YES

What version of gRPC and what language are you using?

GRPC: 1.8.4
language: Objective-C

What operating system (Linux, Windows, …) and version?

iOS

What runtime / compiler are you using (e.g. python version or version of gcc)

Clang

What did you do?

test GRPC online to profile the statbility

What did you expect to see?

not crash

What did you see instead?

crash on low rate

Crashed: com.apple.root.default-qos
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000000

Crashed: com.apple.root.default-qos
0  myapp                          0x1037f08f4 gpr_ref_non_zero (sync.cc:88)
1  myapp                          0x1037ee0b8 grpc_connected_subchannel_ref (subchannel.cc:170)
2  myapp                          0x1037d9a1c pf_pick_locked(grpc_exec_ctx*, grpc_lb_policy*, grpc_lb_policy_pick_args const*, grpc_connected_subchannel**, grpc_call_context_element*, void**, grpc_closure*) (pick_first.cc:182)
3  myapp                          0x1037aca1c pick_callback_start_locked(grpc_exec_ctx*, grpc_call_element*) (client_channel.cc:1145)
4  myapp                          0x1037ac66c start_pick_locked(grpc_exec_ctx*, void*, grpc_error*) (client_channel.cc:1306)
5  myapp                          0x1037af588 grpc_combiner_continue_exec_ctx (combiner.cc:261)
6  myapp                          0x1037bae94 grpc_exec_ctx_flush (exec_ctx.cc:93)
7  myapp                          0x1037b877c pollset_work(grpc_exec_ctx*, grpc_pollset*, grpc_pollset_worker**, long) (ev_poll_posix.cc:1057)
8  myapp                          0x1037b0840 cq_next(grpc_completion_queue*, gpr_timespec, void*) (completion_queue.cc:952)
9  myapp                          0x103794450 __27-[GRPCCompletionQueue init]_block_invoke_2 (GRPCCompletionQueue.m:56)
10 libdispatch.dylib              0x182a9aa54 _dispatch_call_block_and_release + 24
11 libdispatch.dylib              0x182a9aa14 _dispatch_client_callout + 16
12 libdispatch.dylib              0x182aa1bc8 _dispatch_queue_override_invoke$VARIANT$mp + 716
13 libdispatch.dylib              0x182aa7cf4 _dispatch_root_queue_drain + 600
14 libdispatch.dylib              0x182aa7a38 _dispatch_worker_thread3 + 120
15 libsystem_pthread.dylib        0x182d4306c _pthread_wqthread + 1268
16 libsystem_pthread.dylib        0x182d42b6c start_wqthread + 4

Anything else we should know about your project / environment?

no

[srini100]

Looks same as this issue.

[srini100]

@0oneo please post your steps to reproduce this crash.

[0oneo]

@srini100 the crash happens on low rate on our production. On my dev machine, I have never came to this crash

[srini100]

@0oneo Fix for #13327 is in 1.9.x. If you can, please try this version. After some mileage, fix may be backported to 1.8.x.