Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-19061

table_share used for reading statistical tables is not protected

    XMLWordPrintable

Details

    Description

      While reading statistics for a table in function read_statistics_for_table_is_needed we don't protect the table_share fields and there is a chance that multiple threads would try to access it at the same time.

      To see this
      Lets add this patch to read_statistics_for_table

      +fprintf(stderr, "READ %p\n", current_thd); fflush(stderr);
      		 
      +sleep(10);
      		 
      +fprintf(stderr, "DONE %p\n", current_thd); fflush(stderr);
      		 
      +

      and the server output is

       
      		 
      READ 0x7fc870000b00 
      READ 0x7fc874000b00
      		 
      DONE 0x7fc870000b00
      		 
      DONE 0x7fc874000b00

      so different threads are entering the function at the same time.
      So i think we need an exclusive lock to protect the members of table_share

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-18899 Server crashes in Field::set_warning_truncated_wrong_value

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-19407 Assertion `field->table->stats_is_read' failed in is_eits_usable

          • Blocker - Blocks development and/or testing work, production could not run.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-29693 ANALYZE TABLE still flushes table definition cache when engine-independent statistics is used

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Activity

            People

              svoj Sergey Vojtovich
              varun Varun Gupta (Inactive)
              Votes:
              1 Vote for this issue
              Watchers:
              8 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Git Integration

                  Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.