Question

我有一个应用程序，它对内存进行了很多操作。这个应用程序用c＃编写 - 它有单声道运行时间。

我们认为在应用程序内存消耗内存操作时会不断增长。同时这个问题在El Captain上是不可复制的。

如果长时间（数周）工作，它甚至可以达到8或10 GB。

我已经确认没有内存泄漏（重要，可能会导致这种增长）。我已经确认没有任何保留周期阻止收集对象 - 再次，该应用程序在El Captain上完美无缺。

我发现：

几乎所有应用程序内存（不包括150 MB的活动内存）都会进入压缩状态，甚至会转换为磁盘。

根据Xcode Instruments VM Tracker工具 - VM_Allocation区域几乎可以保存所有交换内存

＆LT; --- !!! - 注意

% of Res.   Type    # Regs  Path            Resident Size   Dirty Size  Swapped Size        Virtual Size    Res. %  
100%        *All*   17997   < multiple >    517.21 MiB      240.89 MiB  704.31 MiB <---!!!  2.07 GiB        24% 

% of Res.   Type        # Regs      Path    Resident Size   Dirty Size  Swapped Size        Virtual Size    Res. %  
18%         VM_ALLOCATE 15939       -       90.76 MiB       90.76 MiB   588.81 MiB <---!!!  696.29 MiB      13%

我删除了虚拟内存分配/解除分配的所有出现和堆栈跟踪 - mmap（），munmap（），vm_allocate（），vm_deallocate（），并发现：

对于当前交换的内存页面的每个mmap（），都有相应的成功的munmap（）对于当前交换的内存页面的每个vm_allocate（），都有相应的成功vm_deallocate（）

但

由于某种原因某些vm区域的munmap（）返回＆＃34; 0＆＃34;这意味着成功，但相关页面仍然呈现 - 它们不会返回系统。

不期望 - 私有的，无意义的内存的munmap（）应该导致页面释放。我在我的示例应用中验证了这一点。使用mlock（），madvice（）的任何操作都无助于模仿。

这导致了一个问题，因为GC放弃了这些页面（它们不再被重用），同时它们不是免费的。由于它们不再使用，它们通过压缩然后交换到磁盘。

此外，被遗弃的页面还活着 - 从lldb访问它们不会导致BAD_ACCESS。

有没有人见过这个？

以下是显示问题的日志提取。

   This is VM state evolution in 0x11c5XXXXX range of 1 MB:

   I. allocation, deallocation object in Large objects space

   Type Address Range   Dirty Size  Swapped Size    Resident Size   Virtual Size    Resident %  Protections Path
   VM_ALLOCATE  0x11c500000 - 0x11c600000   1.00 MiB    0 Bytes 1.00 MiB    1.00 MiB    100%    rw-/rwx 

     3    551                      mmap:return [240760570406181]:mmap:  [0x11c500000, 2097152] flags: 4098
                 libsystem_kernel.dylib`__mmap+0xa
                 Drive`mono_valloc+0x69
                 Drive`mono_valloc_aligned+0x22
                 Drive`sgen_alloc_os_memory_aligned+0x23
                 Drive`sgen_los_alloc_large_inner+0x274
                 Drive`sgen_alloc_obj_nolock+0x69
                 Drive`mono_gc_alloc_vector+0x7b
                 0x1063cb0e6
                 0x117429a4a
                 0x1174296d2
                 0x11742881c
                 0x1174286ca
                 0x117428530
                 0x1173a77cd
                 0x11739a81a
                 0x11739a2e1
                 0x11739a213
                 0x116ad373b
                 0x111a2f199
                 0x10df54fc9

     3    303                    munmap:return [240983284059591]:munmap: 0   0x11c500000, 1048576
                 libsystem_kernel.dylib`__munmap+0xa
                 Drive`mono_valloc_aligned+0xd0
                 Drive`sgen_alloc_os_memory_aligned+0x23
                 Drive`sgen_los_alloc_large_inner+0x274
                 Drive`sgen_alloc_obj_nolock+0x69
                 Drive`mono_gc_alloc_vector+0x7b
                 0x1063cb0e6
                 0x117429a4a
                 0x1174296d2
                 0x11742881c
                 0x1174286ca
                 0x117428530
                 0x1173a77cd
                 0x11739a81a
                 0x11739a2e1
                 0x11739a213
                 0x116ad373b
                 0x111a2f199
                 0x10df54fc9
                 Drive`mono_jit_runtime_invoke+0x8e0

   II. SQLITE page cache allocation / deallocation 

   Type Address Range   Dirty Size  Swapped Size    Resident Size   Virtual Size    Resident %  Protections Path
   SQLite page cache    0x11c50f000 - 0x11c51f000   64.00 KiB   0 Bytes 64.00 KiB   64.00 KiB   100%    rw-/rwx 
   SQLite page cache    0x11c51f000 - 0x11c52f000   64.00 KiB   0 Bytes 64.00 KiB   64.00 KiB   100%    rw-/rwx 

   [241059759675635]:vm_allocate:   0x11c50f000, 0x10000

                 libsystem_kernel.dylib`vm_allocate+0x26
                 libsqlite3.dylib`purgeableCacheFetch+0x32a
                 libsqlite3.dylib`sqlite3PagerGet+0x18d
                 libsqlite3.dylib`getAndInitPage+0x47
                 libsqlite3.dylib`sqlite3BtreeMovetoUnpacked+0x52d
                 libsqlite3.dylib`handleDeferredMoveto+0x1e
                 libsqlite3.dylib`sqlite3VdbeExec+0x9b72
                 libsqlite3.dylib`sqlite3_step+0x3cf
                 0x11188e240

   [241097285460026]:vm_deallocate: 0x11c50f000

                 libsystem_kernel.dylib`vm_deallocate
                 libsqlite3.dylib`purgeableCacheDestroy+0x464
                 libsqlite3.dylib`sqlite3PagerClose+0x279
                 libsqlite3.dylib`sqlite3BtreeClose+0x142
                 libsqlite3.dylib`sqlite3LeaveMutexAndCloseZombie+0x192
                 libsqlite3.dylib`sqlite3Close+0x409
                 0x112caf100
                 0x112caee8d
                 0x11188ec28
                 0x112fee6d5
                 Drive`mono_gc_run_finalize+0x3fc
                 Drive`sgen_gc_invoke_finalizers+0x114
                 Drive`finalizer_thread+0x252
                 Drive`start_wrapper+0x22e
                 Drive`inner_start_thread+0x196
                 libsystem_pthread.dylib`_pthread_body+0xb4
                 libsystem_pthread.dylib`_pthread_body
                 libsystem_pthread.dylib`thread_start+0xd


   III. SQLITE page cache deallocation. These three guys are unknown... That's strange - my assumption that the reason that I don't have allocation stack trace for them is dtrace failure - it reports errors a little from time to time

   Type Address Range   Dirty Size  Swapped Size    Resident Size   Virtual Size    Resident %  Protections Path
   VM_ALLOCATE  0x11c5ef000 - 0x11c5f1000   8.00 KiB    0 Bytes 8.00 KiB    8.00 KiB    100%    rw-/rwx 
   VM_ALLOCATE  0x11c5f1000 - 0x11c5f2000   4.00 KiB    0 Bytes 4.00 KiB    4.00 KiB    100%    rw-/rwx 
   VM_ALLOCATE  0x11c5f5000 - 0x11c5fa000   20.00 KiB   0 Bytes 20.00 KiB   20.00 KiB   100%    rw-/rwx 


   IV. FIRST REPRODUCTION <---!!! 0x11c51e000 - mmapped() then munmapped() but still be presented.
   Type Address Range   Dirty Size  Swapped Size    Resident Size   Virtual Size    Resident %  Protections Path
   SQLite page cache    0x11c50e000 - 0x11c51e000   0 Bytes 0 Bytes 0 Bytes 64.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c51e000 - 0x11c529000   44.00 KiB   0 Bytes 44.00 KiB   44.00 KiB   100%    rw-/rwx 
   VM_ALLOCATE  0x11c5ef000 - 0x11c5f1000   8.00 KiB    0 Bytes 8.00 KiB    8.00 KiB    100%    rw-/rwx 
   VM_ALLOCATE  0x11c5f1000 - 0x11c5f2000   4.00 KiB    0 Bytes 4.00 KiB    4.00 KiB    100%    rw-/rwx 
   VM_ALLOCATE  0x11c5f5000 - 0x11c5fa000   20.00 KiB   0 Bytes 20.00 KiB   20.00 KiB   100%    rw-/rwx 


   0    551                      mmap:return [241237210309703]:mmap:   [0x11c51e000, 4096] flags: 4098
                 libsystem_kernel.dylib`__mmap+0xa
                 Drive`mono_valloc+0x69
                 Drive`mono_lock_free_alloc+0x335
                 Drive`sgen_alloc_internal+0x3b
                 Drive`sgen_gray_object_enqueue+0x5c
                 Drive`mono_g_hash_mark+0x11a
                 Drive`job_scan_from_registered_roots+0x18c
                 Drive`sgen_workers_enqueue_job+0x23
                 Drive`enqueue_scan_from_roots_jobs+0x7d
                 Drive`major_copy_or_mark_from_roots+0x36a
                 Drive`major_start_collection+0x155
                 Drive`major_do_collection+0x4e
                 Drive`sgen_perform_collection+0x2a6
                 Drive`sgen_los_alloc_large_inner+0x5d
                 Drive`sgen_alloc_obj_nolock+0x69
                 Drive`mono_gc_alloc_vector+0x7b
                 0x1063cb0e6
                 0x10bd2a7b3
                 0x10bd293d1
                 0x1173a6db6



     2    303                    munmap:return [241257343803100]:munmap: 0    <---!!!    0x11c51e000, 4096
                 libsystem_kernel.dylib`__munmap+0xa
                 Drive`mono_vfree+0x32
                 Drive`desc_retire+0x43
                 Drive`mono_lock_free_free+0x1a9
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x17
                 Drive`pin_stats_tree_free+0x17
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x17
                 Drive`pin_stats_tree_free+0x17
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`pin_stats_tree_free+0x20
                 Drive`sgen_pin_stats_reset+0x10
                 Drive`collect_nursery+0x414
                 Drive`sgen_perform_collection+0x1b1


   V. Done - all the memory in the range is abandoned

   Type Address Range   Dirty Size  Swapped Size    Resident Size   Virtual Size    Resident %  Protections Path
   VM_ALLOCATE  0x11c51c000 - 0x11c51e000   0 Bytes 8.00 KiB    0 Bytes 8.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c51e000 - 0x11c53c000   0 Bytes 120.00 KiB  0 Bytes 120.00 KiB  0%  rw-/rwx 
   VM_ALLOCATE  0x11c53c000 - 0x11c550000   0 Bytes 80.00 KiB   0 Bytes 80.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c550000 - 0x11c568000   0 Bytes 96.00 KiB   0 Bytes 96.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c568000 - 0x11c569000   0 Bytes 4.00 KiB    0 Bytes 4.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c569000 - 0x11c57d000   0 Bytes 80.00 KiB   0 Bytes 80.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c57d000 - 0x11c589000   0 Bytes 48.00 KiB   0 Bytes 48.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c589000 - 0x11c58b000   0 Bytes 8.00 KiB    0 Bytes 8.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c58b000 - 0x11c58c000   0 Bytes 4.00 KiB    0 Bytes 4.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c58c000 - 0x11c594000   0 Bytes 32.00 KiB   0 Bytes 32.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c594000 - 0x11c5b3000   0 Bytes 124.00 KiB  0 Bytes 124.00 KiB  0%  rw-/rwx 
   VM_ALLOCATE  0x11c5b3000 - 0x11c5b5000   0 Bytes 8.00 KiB    0 Bytes 8.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c5b5000 - 0x11c5c9000   0 Bytes 80.00 KiB   0 Bytes 80.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5c9000 - 0x11c5cd000   0 Bytes 16.00 KiB   0 Bytes 16.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5cd000 - 0x11c5d1000   0 Bytes 16.00 KiB   0 Bytes 16.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5d1000 - 0x11c5df000   0 Bytes 56.00 KiB   0 Bytes 56.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5df000 - 0x11c5ee000   0 Bytes 60.00 KiB   0 Bytes 60.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5ee000 - 0x11c5ef000   0 Bytes 4.00 KiB    0 Bytes 4.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c5ef000 - 0x11c5f1000   0 Bytes 8.00 KiB    0 Bytes 8.00 KiB    0%  rw-/rwx 
   VM_ALLOCATE  0x11c5f1000 - 0x11c5f5000   0 Bytes 16.00 KiB   0 Bytes 16.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5f5000 - 0x11c5fa000   0 Bytes 20.00 KiB   0 Bytes 20.00 KiB   0%  rw-/rwx 
   VM_ALLOCATE  0x11c5fa000 - 0x11c619000   0 Bytes 124.00 KiB  0 Bytes 124.00 KiB  0%  rw-/rwx

munmap（）不会将页面返回到macOS Sierra上的系统

0 个答案: