Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-3279

LP:675185 - [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU

Details

    • Bug
    • Status: Closed (View Workflow)
    • Minor
    • Resolution: Fixed
    • None
    • None
    • None

    Description

      Symptoms are: After mysql server upgrades + restarts the old mysqld_safe keeps running and consumes 100% cpu, strace shows:
      wait4(4294967295, 0x7fffb3b3d59c, 0, NULL) = -1 ECHILD (No child ...
      wait4(4294967295, 0x7fffb3b3d59c, 0, NULL) = -1 ECHILD (No child ...
      wait4(4294967295, 0x7fffb3b3d59c, 0, NULL) = -1 ECHILD (No child ...
      For more info see the dupes, particularily bug 105457. Does not happen always, for reliable test case see below.

      This is a bug (race condition) in dash, partly fixed by http://git.kernel.org/?p=utils/dash/dash.git;a=commit;h=3800d4934391b144fd261a7957aea72ced7d47ea . This fixes the test case and mysqld_safe, but introduces another regression: http://eeek.borgchat.net/lists/dash/msg00268.html (patch for that in the thread)

      TEST CASE: Script in the commit message (link above). Allows to reproduce this always, even on Karmic still.

      (Proposed fix of using #Unable to render embedded object: File (/bin/bash instead of #) not found./bin/sh is not as straigtforward as expected. bash called as sh goes into sh compatibility mode, called as bash it may behave subtle differently)

      NOTES: mysqld_safe was replaced by an upstart job in Lucid. But Hardy has support for 3 more years, justifiying a fix.

      Attachments

        Activity

          Ascending order - Click to sort in descending order
          View 6 older comments
          knielsen Kristian Nielsen added a comment -

          Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU
          I fixed this for mariadb by adding a patch to the .deb packaging that puts #!/bin/bash in the header of mysqld_safe.

          Fix will be available from 5.1.52 and 5.2.4.

          knielsen Kristian Nielsen added a comment - Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU I fixed this for mariadb by adding a patch to the .deb packaging that puts #!/bin/bash in the header of mysqld_safe. Fix will be available from 5.1.52 and 5.2.4.
          knielsen Kristian Nielsen added a comment -

          Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU
          Fixed in MariaDB 5.2.4 and 5.1.53

          knielsen Kristian Nielsen added a comment - Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU Fixed in MariaDB 5.2.4 and 5.1.53
          ratzpo Rasmus Johansson (Inactive) added a comment -

          Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU
          I tested the testcase in the commit on Precise and there seem to no issue there
          (probably fixed there).

          Also, it is not the right approach to change #Unable to render embedded object: File (/bin/sh to #) not found./bin/bash since
          former invokes POSIX compatibility mode and if dash has problems on any
          platform, then that should be fixed rather than changing it in mysqld_safe or
          #!/bin/sh needs to pointed elsewhere (or with update-alternatives).

          Regarding the init scripts, I see that Percona Server is not packaged with
          upstart script (hence vulnerable to this if on a platform with a buggy dash) as
          mysql-server-55 does. I will open a separate issue to add that.

          ratzpo Rasmus Johansson (Inactive) added a comment - Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU I tested the testcase in the commit on Precise and there seem to no issue there (probably fixed there). Also, it is not the right approach to change # Unable to render embedded object: File (/bin/sh to #) not found. /bin/bash since former invokes POSIX compatibility mode and if dash has problems on any platform, then that should be fixed rather than changing it in mysqld_safe or #!/bin/sh needs to pointed elsewhere (or with update-alternatives). Regarding the init scripts, I see that Percona Server is not packaged with upstart script (hence vulnerable to this if on a platform with a buggy dash) as mysql-server-55 does. I will open a separate issue to add that.
          ratzpo Rasmus Johansson (Inactive) added a comment -

          Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU
          lp:1053183 is the issue for providing upstart scripts with percona-server.

          ratzpo Rasmus Johansson (Inactive) added a comment - Re: [Hardy SRU] dash bug causes mysqld_safe to spin at 100% CPU lp:1053183 is the issue for providing upstart scripts with percona-server.
          ratzpo Rasmus Johansson (Inactive) added a comment -

          Launchpad bug id: 675185

          ratzpo Rasmus Johansson (Inactive) added a comment - Launchpad bug id: 675185

          People

            knielsen Kristian Nielsen
            jakobunterwurzacher Jakob Unterwurzacher (Inactive)
            Votes:
            0 Vote for this issue
            Watchers:
            0 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.