Bug 182166 – ServicesController::refreshExistingServices invokes NSSharingService sharingServicesForItems in a background thread

• Status: RESOLVED
• Resolution: WONTFIX
• Component: WebKit2

[Ryosuke Niwa]

NSSharingService sharingServicesForItems calls into AppKit so can't be called in a background thread but we're doing that in ServicesController::refreshExistingServices

[Ryosuke Niwa]

Main Thread Checker: UI API called on a background thread: -[NSCell image]
PID: 33220, TID: 7447672, Thread name: (none), Queue name: com.apple.WebKit.ServicesController, QoS: 0
Backtrace:
4   ShareKit                            0x00007fff600a7d16 __72+[SHKSandbox filteredItemsFromAttributedString:processWithPID:textView:]_block_invoke + 348
5   Foundation                          0x00007fff4165a6ca -[NSAttributedString enumerateAttribute:inRange:options:usingBlock:] + 397
6   ShareKit                            0x00007fff600a7a59 +[SHKSandbox filteredItemsFromAttributedString:processWithPID:textView:] + 421
7   ShareKit                            0x00007fff600a6759 +[SHKSandbox filteredItemsFromSingleItem:processWithPID:] + 218
8   ShareKit                            0x00007fff600a65b3 +[SHKSandbox filteredItemsFromItems:processWithPID:] + 439
9   ShareKit                            0x00007fff600a06ad +[SHKSharingService sharingServicesForItems:mask:invokedByPicker:] + 249
10  AppKit                              0x00007fff3cb1a3fa +[NSSharingService sharingServicesForItems:mask:] + 67
11  WebKit                              0x00000001050fe7fa _ZN6WebKitL29hasCompatibleServicesForItemsEP7NSArray + 42
12  WebKit                              0x00000001050fe70f ___ZN6WebKit18ServicesController23refreshExistingServicesEb_block_invoke + 495
13  libdispatch.dylib                   0x000000010962ec3d _dispatch_call_block_and_release + 12
14  libdispatch.dylib                   0x0000000109626d1f _dispatch_client_callout + 8
15  libdispatch.dylib                   0x000000010963cbac _dispatch_queue_serial_drain + 1169
16  libdispatch.dylib                   0x000000010962e790 _dispatch_queue_invoke + 322
17  libdispatch.dylib                   0x000000010963dfbb _dispatch_root_queue_drain_deferred_wlh + 785
18  libdispatch.dylib                   0x0000000109642e94 _dispatch_workloop_worker_thread + 892
19  libsystem_pthread.dylib             0x00000001096a302b _pthread_wqthread + 980
20  libsystem_pthread.dylib             0x00000001096a2c45 start_wqthread + 13

This is done because calling it on the main thread caused noticeable delays. The API was made safe to call on a background thread via <rdar://problem/18139613> but has since regressed. Fixing the regression is tracked in <rdar://problem/32116152> and others.

And this is <rdar://problem/31798317>

[Tim Horton]

Right, what Dan said.