Thread/STOPPER deals with the inevitable Db2 "problem" threads that arise from operational mistakes, network failures, application errors and runaway queries. These problematic Db2 threads can consume considerable system resources, create serious contention problems and impair the performance and availability of critical systems and data. Thread/ STOPPER lets authorized users cancel such threads gracefully — before they impact your system and disrupt large numbers of users. It can also clear the way for critical applications and utilities to run without contention.
Although IBM improves the Db2 CANCEL command with each release, cases remain where CANCEL doesn't work:
- the CANCEL THREAD and CANCEL DDF THREAD commands have no effect unless a thread is processing in Db2. Threads executing within an application or the communications network don't terminate.
- the Db2 and QMF governors only limit individual instances of dynamic SQL statements. Statically bound applications and looping programs are not effected.
- Db2 "marks" an inactive database access thread (DBAT) as cancelled, but cancellation is actually deferred until the thread becomes active again. Thread/STOPPER can DROP the communication connections which underlie the thread to terminate the thread right away.
When threads fail to respond to normal Db2 cancellation processing, Thread/SERIES can issue Db2, z/OS, TCP/IP, SNA/VTAM, IMS and/or CICS commands — separately or in combination — to escalate cancellation and terminate the thread.
Thread/SENTRY provides a rule based, expert system to deal with the inevitable operational mistakes, network failures, application errors and runaway queries that create problematic Db2 threads. Thread/SENTRY is intelligent enough to resolve Db2 problem threads without human intervention. It works tirelessly, around the clock, to safeguard your Db2 subsystems and their users. Thread/SENTRY detects Db2 problem threads in real-time and takes fast, corrective action to resolve problems that threaten Db2 performance and availability.
Thread/SENTRY wakes up, at an interval you specify, to monitor Db2 thread and lock activity. It acts like a skilled operator, DBA or systems programmer using the rules you establish to evaluate information and make decisions. You can predefine Db2 "problem" threads in terms of threshold measurements such as CPU time, idleness or number of SQL statements executed.
Thread/SENTRY will issue a warning or cancel the thread when it detects a violation. It can also request a reply from the console operator or call a site-written program to decide what to do. Thread/ SENTRY acts quickly and automatically, before your system is impacted and large numbers of users are disrupted.