IsActive timeout issue

Interviewer - Server > Administration and maintenance > IsActive timeout issue

When a cluster runs survey projects that contain substantial amounts of routing logic, high CPU usage on the Interview Tier can result in timeouts when the Web Tier checks to ensure that the interviewing server is still active. When these IsActive calls timeout, failovers occur, which in turn can result in cluster instability.

A good indication that the priority of the main interview thread pool should be lowered, in order to allow IsActive calls to be processed under high load, is whenIsActive timeouts (that are not associated with a server or application pool restart) occur. High CPU usage on the Interview Tier servers is also a good indication that the priority of the main interview thread pool should be lowered.

Use the following log file query to group IsActive timeouts into 15 minute intervals and determine if excessive IsActive timeouts are occurring on the Web Tier:

SELECT
  DateTime.DateOnly() As Day,
  CText(DateTime.DatePart('h'))+':'+CText(DateTime.DatePart('n')/15 * 15) As QuarterHour,
  COUNT(*) As IsActiveErrors
FROM VDATA
WHERE LogEntry.Find('IsActive') >= 0 AND LogLevel = {warning}
GROUP BY
  DateTime.DateOnly(),
  DateTime.DatePart('h'),
  DateTime.DatePart('n')/15
ORDER BY
  DateTime.DateOnly(),
  DateTime.DatePart('h'),
  DateTime.DatePart('n')/15

To lower the main interview thread pool priority

1 Configure the registry in order to resolve the IsActive timeout issue. Add the string value InterviewWorkerThreadPriority, with a value of Below Normal or Normal (the default value), under the following registry key:

SOFTWARE\\SPSS\\mrInterview\\3\\Interviewing

2 After InterviewWorkerThreadPriority is defined, the registry can be further configured to control the High Priority Thread Pool size (the threads are used to handle IsActive and PercentLoaded calls). Add the DWORD value DefaultHighPriorityThreadPoolSize, with a value of -10 to 20, under the following registry key:

SOFTWARE\\SPSS\\mrInterview\\3\\Interviewing

A negative value indicates that the thread number will be a factor of the available CPU; the default value is 2.

3 Reset IIS.