firebase-ios-sdk: [APMIdentity appInstanceID] main thread block

[REQUIRED] Step 1: Describe your environment

• Xcode version: 11.6
• Firebase SDK version: 6.31.0
• Firebase Component: Analytics (Auth, Core, Database, Firestore, Messaging, Storage, etc)
• Installation method: CocoaPods

[REQUIRED] Step 2: My Question

Same issue there,For iOS 14,we have to update it. when update ‘Firebase/Analytics’ to 6.31.0,It happens very ofen.now this is our top one main thread block.Please try to fix it.

Sdk version： ‘Firebase/Analytics’ 6.31.0 Google-Mobile-Ads-SDK (>= 7.55.0)

Key Stack Info Below：

Thread 0:
0 libsystem_kernel.dylib 0x188acb93c kevent_id (in libsystem_kernel.dylib) + 8
1 libdispatch.dylib 0x18892bbf0 _dispatch_kq_poll (in libdispatch.dylib) + 332
2 libdispatch.dylib 0x18892c6dc _dispatch_event_loop_wait_for_ownership$VARIANT$mp (in libdispatch.dylib) + 412
3 libdispatch.dylib 0x18891be9c DISPATCH_WAIT_FOR_QUEUE (in libdispatch.dylib) + 296
4 libdispatch.dylib 0x18891bad4 _dispatch_sync_f_slow (in libdispatch.dylib) + 140
5 XXXX 0x102398bb4 -[APMIdentity appInstanceID] (in XXXX) + 144
6 XXXX 0x1023ac194 -[APMIdentifiers appInstanceID] (in XXXX) + 188
7 XXXX 0x10252a9a8 GADAnalyticsAdRequestDictionary (in XXXX) + 132
8 XXXX 0x1024eb840 GADAnalyticsSettingsSignalSource (in XXXX) + 168
9 XXXX 0x10251bb84 GAD_GADSignals_arm64_7_55_0 (in XXXX) + 3868
10 libdispatch.dylib 0x18896ca38 _dispatch_call_block_and_release (in libdispatch.dylib) + 24
11 libdispatch.dylib 0x18896d7d4 _dispatch_client_callout (in libdispatch.dylib) + 16
12 libdispatch.dylib 0x18891b004 _dispatch_main_queue_callback_4CF$VARIANT$mp (in libdispatch.dylib) + 1068
13 CoreFoundation 0x188ebec1c CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE (in CoreFoundation) + 12
14 CoreFoundation 0x188eb9b54 __CFRunLoopRun (in CoreFoundation) + 1924
15 CoreFoundation 0x188eb90b0 CFRunLoopRunSpecific (in CoreFoundation) + 436
16 GraphicsServices 0x18b0b979c GSEventRunModal (in GraphicsServices) + 104
17 UIKitCore 0x1b56ef978 UIApplicationMain (in UIKitCore) + 212
18 XXXX 0x1030560ec _main (in XXXX) (main.m:49)
19 libdyld.dylib 0x18897e8e0 start (in libdyld.dylib) + 4

Thread 42:
0 libsystem_kernel.dylib 0x188acb93c kevent_id (in libsystem_kernel.dylib) + 8
1 libdispatch.dylib 0x18892bbf0 _dispatch_kq_poll (in libdispatch.dylib) + 332
2 libdispatch.dylib 0x18892c2a0 _dispatch_event_loop_wake_owner$VARIANT$mp (in libdispatch.dylib) + 368
3 libdispatch.dylib 0x18891cc44 _dispatch_waiter_wake (in libdispatch.dylib) + 60
4 libdispatch.dylib 0x18891bf70 _dispatch_sync_complete_recurse (in libdispatch.dylib) + 60
5 libdispatch.dylib 0x18891bffc _dispatch_sync_invoke_and_complete_recurse (in libdispatch.dylib) + 88
6 libdispatch.dylib 0x18891baf0 _dispatch_sync_f_slow (in libdispatch.dylib) + 168
7 XXXX 0x102398bb4 -[APMIdentity appInstanceID] (in XXXX) + 144
8 XXXX 0x1023d2a20 -[APMMeasurement(Event) createRawEventMetadataWithUserAttributes:] (in XXXX) + 340
9 XXXX 0x1023d53ec -[APMMeasurement(Event) writeEvent:isPublicEvent:isRealtime:] (in XXXX) + 796
10 XXXX 0x1023d2888 __49-[APMMeasurement(Event) writeEventOnWorkerQueue:]_block_invoke (in XXXX) + 604
11 XXXX 0x1023beda8 -[APMSqliteStore performTransactionWithError:block:] (in XXXX) + 176
12 XXXX 0x10238bb14 -[APMDatabase performTransaction:] (in XXXX) + 48
13 XXXX 0x1023d254c -[APMMeasurement(Event) writeEventOnWorkerQueue:] (in XXXX) + 820
14 XXXX 0x1023d20a8 -[APMMeasurement(Event) handleEventOnWorkerQueue:] (in XXXX) + 540
15 XXXX 0x10239e580 -[APMMeasurement logEventOnWorkerQueue:notifyEventListeners:] (in XXXX) + 148
16 XXXX 0x10239e378 -[APMMeasurement logEventOnWorkerQueueWithOrigin:isPublicEvent:name:parameters:timestamp:enabled:ignoreEnabled:ignoreInterceptor:interceptor:addedScreenParameters:] (in XXXX) + 340
17 XXXX 0x10239e17c __151-[APMMeasurement logEventWithOrigin:isPublicEvent:name:parameters:timestamp:enabled:ignoreEnabled:ignoreInterceptor:interceptor:addedScreenParameters:]_block_invoke (in XXXX) + 68
18 XXXX 0x1023a9f84 __51-[APMScheduler scheduleOnWorkerQueueBlockID:block:]_block_invoke (in XXXX) + 44
19 libdispatch.dylib 0x18896ca38 _dispatch_call_block_and_release (in libdispatch.dylib) + 24
20 libdispatch.dylib 0x18896d7d4 _dispatch_client_callout (in libdispatch.dylib) + 16
21 libdispatch.dylib 0x188916320 _dispatch_lane_serial_drain$VARIANT$mp (in libdispatch.dylib) + 592
22 libdispatch.dylib 0x188916e3c _dispatch_lane_invoke$VARIANT$mp (in libdispatch.dylib) + 428
23 libdispatch.dylib 0x18891f4a8 _dispatch_workloop_worker_thread (in libdispatch.dylib) + 596
24 libsystem_pthread.dylib 0x188b4d114 _pthread_wqthread (in libsystem_pthread.dylib) + 304

Thread 68:
0 libsystem_kernel.dylib 0x188abf0f4 mach_msg_trap (in libsystem_kernel.dylib) + 8
1 libsystem_kernel.dylib 0x188abe5a0 mach_msg (in libsystem_kernel.dylib) + 72
2 libdispatch.dylib 0x188924880 _dispatch_mach_send_and_wait_for_reply (in libdispatch.dylib) + 500
3 libdispatch.dylib 0x188924d10 dispatch_mach_send_with_result_and_wait_for_reply$VARIANT$mp (in libdispatch.dylib) + 52
4 libxpc.dylib 0x188b8391c xpc_connection_send_message_with_reply_sync (in libxpc.dylib) + 204
5 Foundation 0x189aafa28 NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY (in Foundation) + 12
6 Foundation 0x189892f60 -[NSXPCConnection sendInvocation:orArguments:count:methodSignature:selector:withProxy:] (in Foundation) + 3608
7 CoreFoundation 0x188f3276c forwarding (in CoreFoundation) + 552
8 CoreFoundation 0x188f3475c forwarding_prep_0 (in CoreFoundation) + 92
9 CoreServices 0x1b1896ce4 -[LSApplicationWorkspace deviceIdentifierForAdvertising] (in CoreServices) + 160
10 AdSupport 0x198f70a60 -[ASIdentifierManager advertisingIdentifier] (in AdSupport) + 56
11 XXXX 0x100afc998 -[APMASIdentifierWrapper resettableDeviceIDStringIfAvailable] (in XXXX) + 140
12 XXXX 0x1023997e0 __32-[APMIdentity updateIdentifiers]_block_invoke (in XXXX) + 452
13 libdispatch.dylib 0x18896ca38 _dispatch_call_block_and_release (in libdispatch.dylib) + 24
14 libdispatch.dylib 0x18896d7d4 _dispatch_client_callout (in libdispatch.dylib) + 16
15 libdispatch.dylib 0x188916320 _dispatch_lane_serial_drain$VARIANT$mp (in libdispatch.dylib) + 592
16 libdispatch.dylib 0x188916e3c _dispatch_lane_invoke$VARIANT$mp (in libdispatch.dylib) + 428
17 libdispatch.dylib 0x18891f4a8 _dispatch_workloop_worker_thread (in libdispatch.dylib) + 596
18 libsystem_pthread.dylib 0x188b4d114 _pthread_wqthread (in libsystem_pthread.dylib) + 304

I think it’s thread 68 call [APMIdentity updateIdentifiers] and trigger xpc_connection_send_message.this may cost a lot of time sometimes.So when in main thread call -[APMIdentity appInstanceID],we must wait xpc done and main thrad block happen.maybe can we dispatch GADAnalyticsAdRequestDictionary to other thread?

If you need more info,please reply me thanks.