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  1. WiredTiger
  2. WT-13299

Backup may block WiredTiger statistics gathering

    • Type: Icon: Task Task
    • Resolution: Cannot Reproduce
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Backup
    • None
    • Storage Engines

      Taking a backup blocks FTDC gathering while the backup commences, I haven't yet determined if that is only when the backup starts or if it is for the full duration of the backup.

      This can reproduced easily with the following patch using the incr_backup test:

      diff --git a/test/csuite/incr_backup/main.c b/test/csuite/incr_backup/main.c
      index f8de2578e..e7e48de6a 100644
      --- a/test/csuite/incr_backup/main.c
      +++ b/test/csuite/incr_backup/main.c
      @@ -36,11 +36,11 @@
       #include <sys/wait.h>
       #include <signal.h>
      
      -#define ITERATIONS 10
      -#define MAX_NTABLES 100
      +#define ITERATIONS 13
      +#define MAX_NTABLES 1000
      
      -#define MAX_KEY_SIZE 100
      -#define MAX_VALUE_SIZE 10000
      +#define MAX_KEY_SIZE 1000
      +#define MAX_VALUE_SIZE 1000000
       #define MAX_MODIFY_ENTRIES 10
       #define MAX_MODIFY_DIFF 500
      
      @@ -49,7 +49,7 @@
       #define KEY_FORMAT "key-%d-%d"
       #define TABLE_FORMAT "key_format=S,value_format=u"
      
      -#define CONN_CONFIG_COMMON "timing_stress_for_test=[backup_rename]"
      +#define CONN_CONFIG_COMMON "timing_stress_for_test=[backup_rename],statistics=(all),statistics_log=(wait=1,json=true)"
      
       #define NUM_ALLOC 5
       static const char *alloc_sizes[] = {"512B", "8K", "64K", "1M", "16M"};
      

      Once the test completes open the WiredTigerStat* file and the FTDC appears to have gaps in it.

      Scope:

      • Reproduce this failure
      • If possible fix, if not possible document the behaviour

            Assignee:
            backlog-server-storage-engines [DO NOT USE] Backlog - Storage Engines Team
            Reporter:
            luke.pearson@mongodb.com Luke Pearson
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              Created:
              Updated:
              Resolved: