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  1. ZABBIX BUGS AND ISSUES
  2. ZBX-10031

On Windows some thread local variables are actually not thread local

    Details

    • Type: Incident report
    • Status: Closed
    • Priority: Trivial
    • Resolution: Fixed
    • Affects Version/s: 2.4.6
    • Fix Version/s: 3.0.0alpha5
    • Component/s: Agent (G)
    • Environment:
      Windows Server 2008

      Description

      See sub-issue (123) in ZBXNEXT-1263.

      This is a regression since ZBX-8796, ZBXNEXT-101. process_type, process_num, server_num are NOT thread local variables.

      src/zabbix_agent/zabbix_agentd.c

      ZBX_THREAD_LOCAL unsigned char  process_type    = 255;  /* ZBX_PROCESS_TYPE_UNKNOWN */
      ZBX_THREAD_LOCAL int            process_num;
      ZBX_THREAD_LOCAL int            server_num      = 0;
      

      src/zabbix_agent/listener.c, etc.

      extern unsigned char    process_type, program_type;
      extern int              server_num, process_num;
      

      According to Microsoft this should produce (compile time?) errors. We don't have neither errors, nor warnings in our build environment regarding this problem.

      You must use the thread attribute for the declaration and the definition of thread local data,
      regardless of whether the declaration and definition occur in the same file or separate files.
      For example, the following code generates an error: 
      
      #define Thread   __declspec( thread )
      extern int tls_i;     /* This generates an error, because the   */
      int Thread tls_i;     /* declaration and the definition differ. */
      

      This causes listener threads reusing the same number due to race condition during thread initialization when agent is started.

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            • Assignee:
              Unassigned
              Reporter:
              sandis.neilands Sandis Neilands (Inactive)
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              • Created:
                Updated:
                Resolved: