1111gg Hang Detection Hang Detection

Jeremiah Wiltonhttp://www.ora-600.net

11g Diagnosability Infrastructure

ADR / IPS (adrci, DIAG, dia0) Prelim connection (excellent) Hang detection (cyclic, acyclic) Test case builder Health checks (on-demand, reactive) Interfaces to DB/Grid Control Advisers (SQL Repair)

Cyclic Hangs

Sessions deadlocked through chain of resources

Generates ORA-60 like normal deadlocks Demo...

Acyclic Hangs

11g harder to hang Chains of resource holding

Steady (seconds_in_wait increasing) Takes min 300 seconds RAC only Quietly generates a trace file (no alert log message)

<SID>_DIA0_<PID>_<n>.trc test01_DIA0_3867_1.trc Message in DIA0 trace “About to produce dumps”

Demo

My hopes for hang detection

Amazon's model Customizable / scriptable

When to dump What to dump

Integrate with ADR

Real-world hangs

Hang with LC Pin pile-up (typical) Hang with BCT writer I/O hanging (bug?) Database completely disabled but failure does

not qualify as a hang

Prelim connection

Can connect to a totally hung instance Use your own or attach to an existing process Hanganalyze, systemstate, errorstack Run queries on x$ structs - results to screen or

trace Pull ASH data Can you do prelim from non-SQL*Plus?

Other data sourceswhen you can log in

ASH – your first stop for performance Hanganalyze Errorstack

Talk back

We need to report typical events to Oracle Support is a sufficient route (enhancement

request) Bring them good data Tell me or use your sales channels to get it on

the agenda