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  1. Core Server
  2. SERVER-16269

Wired Tiger blocks queries and updates for many seconds.

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: 2.8.0-rc0
    • Fix Version/s: None
    • Component/s: Storage
    • Labels:
    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL

      Description

      Comparing MMAP to WiredTiger on an 8 core server with 32GB Ram and local SSD (AWS Instance).

      Throwing a mix of insert/update/query at the server and wiredtiger viewed in mongostat shows really inconsistent performance - also many operations in log are poking about the 100ms mark with inserts taking >1s in some cases. I dont see this inconsistency with mmap v1.

      mmapv1 engine output from mongostat looks like this.

      insert query update delete getmore command flushes mapped vsize    res faults     locked db idx miss % qr|qw ar|aw netIn netOut conn     time
        3076  8761   5582     *0       0     2|0       0   6.0g 12.5g 415.0m      0         :0.0%          0 37|85 42|86   10m     9m  129 15:33:16
        2789 10304   5979     *0       0     1|0       0   6.0g 12.5g 418.0m      0         :0.0%          0 42|82 44|83   11m    11m  129 15:33:17
        3668  8509   4778     *0       0     1|0       0   6.0g 12.5g 412.0m      0         :0.0%          0 10|65 39|67   10m     9m  129 15:33:18
        4151  8757   5172     *0       0     1|0       0   6.0g 12.5g 472.0m      0         :0.0%          0 29|94 32|95   11m     9m  129 15:33:19
        3019  7988   6096     *0       0     1|0       0   6.0g 12.5g 477.0m      0         :0.0%          0 44|78 48|79   11m     9m  129 15:33:20
        3661  7152   5647     *0       0     2|0       0   6.0g 12.5g 478.0m      0         :0.0%          0 53|75 56|75   11m     8m  129 15:33:21
        2378  7132   6574     *0       0     1|0       0   6.0g 12.5g 479.0m      0         :0.0%          0 32|91 35|92   11m     8m  129 15:33:22
        2437  8355   6379     *0       0     1|0       0   6.0g 12.5g 484.0m      0         :0.0%          0 41|83 43|84   11m     9m  129 15:33:23
        2334  8889   5756     *0       0     1|0       0   6.0g 12.5g 483.0m      0         :0.0%          0 52|72 54|73   10m     9m  129 15:33:24

      WT looks like this

      insert query update delete getmore command flushes mapped vsize res faults     locked db idx miss % qr|qw ar|aw netIn netOut conn     time
        2348  8786   5922     *0       0     2|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   10m     9m  129 15:35:48
        9918 30670  21542     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   39m    34m  129 15:35:49
       11902 33152  20733     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   41m    37m  129 15:35:50
        3801  8540   5223     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   11m     9m  129 15:35:51
          *0    *0     *0     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   79b    13k  129 15:35:52
        2934  7013   5251     *0       0     2|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   10m     8m  129 15:35:53
         548  1183    896     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a    1m     1m  129 15:35:54
          52    91     77     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a  159k   118k  129 15:35:55
        5622 14617  12105     *0       0     1|0     n/a    n/a   n/a n/a    n/a           n/a        n/a   n/a   n/a   22m    16m  129 15:35:56

        Attachments

        1. gdbprof.html
          6.93 MB
        2. incident1.html
          934 kB
        3. incident1.png
          incident1.png
          337 kB
        4. incident1-blocker.png
          incident1-blocker.png
          321 kB
        5. incident1-waiters-1.png
          incident1-waiters-1.png
          98 kB
        6. incident1-waiters-2.png
          incident1-waiters-2.png
          93 kB
        7. incident2.html
          964 kB
        8. isse.html
          134.76 MB
        9. stats.WT.nocomp.csv.max.png
          stats.WT.nocomp.csv.max.png
          580 kB
        10. try13.png
          try13.png
          307 kB
        11. try14.png
          try14.png
          238 kB
        12. try15.png
          try15.png
          169 kB
        13. WiredTiger.csv.max.png
          WiredTiger.csv.max.png
          343 kB

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                  Updated:
                  Resolved: