4.2.8 Collecting I/O filter trace information
I/O filter trace information indicates the trace information collected when the input and output filter function implemented in a module is executed.
The I/O filter trace information collection functionality can be used when the HWSRequestLog directive is specified and filter is specified in the HWSRequestLogType directive. I/O filter trace information is useful for isolating an error that occurred in a module filter. Due to the large amount of data output for I/O filter trace information, we do not recommend using it for anything aside from debugging.
- Organization of this subsection
(1) Trace information format
The items below are output for I/O filter trace information.
Note that in the following coding, server-process-ID is used in the format when the prefork MPM is used in the UNIX version. In place of server-process-ID, server-process-ID:server-thread-ID is displayed for the worker MPM in the UNIX version, and server-thread-ID is displayed in the Windows version.
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For an input filter call
[Time]Δ(server-process-ID)ΔhwsΔ:Δin-filter#Δ-->Δ(filter-name[filter-type-number])
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For an input filter return
[Time]Δ(server-process-ID)ΔhwsΔ:Δin-filter#Δ<--Δ(filter-name[filter-type-number])(returned-value)
- Legend:
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Δ: Space
#: For the output filter, in-filter is changed to out-filter.
- (Output example)
[Tue Nov 21 15:18:40 2006] (1716) hws : in-filter --> (core_in[60]) [Tue Nov 21 15:18:40 2006] (1716) hws : in-filter <-- (core_in[60])(0)