I am looking of a description of the output generated by the !SyncBlk command of SOS.
Particularly I found no useful explanation on the column "MonitorHeld". This column shows high values in a series of crash dumps.
Example:
0:000> !SyncBlk
Index SyncBlock MonitorHeld Recursion Owning Thread Info SyncBlock Owner
44 0000000005a5c228 1 1 000000000e7a6740 2304 273 000000019f858cd0 System.Object
48 000000000579bae8 1 1 000000000e7a72e0 2370 275 000000015f999900 System.Object
52 000000000579b9c8 1 1 0000000011bbd3b0 1e98 295 00000000ff89fe08 System.Object
54 000000000579b938 1 1 000000000e7a38c0 1be4 249 000000013f8aa888 System.Object
108 0000000005a5bfe8 1 1 000000000e79f300 224c 242 00000000ff8a5828 System.Object
110 0000000005a5c078 1 1 000000000e79ca50 2290 262 000000015f9a8020 System.Object
112 0000000005a5c108 1 1 0000000011bb70e0 1d38 236 000000015f99e408 System.Object
114 000000000579b620 1 1 0000000011bb93c0 1884 304 00000001bf974a90 System.Object
124 0000000005a44d48 1 1 000000000e7a6170 2300 272 000000019f853fe8 System.Object
146 0000000005a44688 99 1 000000000588cbf0 13e0 38 000000017f71c4f8 System.Object
155 0000000005a44f88 1 1 0000000011bba530 2274 301 000000019f82f120 System.Object
157 0000000005a45018 1 1 0000000011bbf0c0 2034 290 000000015f952980 System.Object
Can anyone explain the "99" in column "MonitorHeld"?
Has anyone a a link to a complete reference documentation of this command?
Thanks, Alex
The MonitorHeld refers to how many monitors are held by that specific SyncBlk.
Each time you have contention on a lock, you'll have 1 owner held syncblk. Each waiter on a lock holds 2.
Your 99 means that you have one object "owning" the lock, and 49 objects waiting on the lock (49x2 + 1 = 99).
The best discussion and detailed explanation of !syncblk I've found is this one by Tess Ferrandez.