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https://issues.apache.org/jira/browse/TS-1102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13214638#comment-13214638
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Uri Shachar commented on TS-1102:
---------------------------------
First thing first: --disable-diags does not do anything (it sets TS_USE_DIAGS
to 0 but Diags.h tests if is defined or not)....
I haven't been able to reproduce anything close to a 15% degradation, but i
have seen 1.7%. Looks like the increased overhead of always calling the
multiple argument function outweighs everything else. When I do:
-#define Diag(tag, fmt, ...) diags->log(tag, DTA(DL_Diag), fmt,
##__VA_ARGS__)
+#define Diag(tag, fmt, ...) if (diags->on(tag)) diags->log(tag,
DTA(DL_Diag), fmt, ##__VA_ARGS__)
and remove the diags->on(tag) call in the beginning of Diags::log the we get
the slight perf boost I expected when a tag is turned on, and no impact when
diags is turned off.
Attaching a patch (with the DebugOn removal) + the benchmark results that I got.
> Cleanup obsolete debugging code
> -------------------------------
>
> Key: TS-1102
> URL: https://issues.apache.org/jira/browse/TS-1102
> Project: Traffic Server
> Issue Type: Bug
> Components: Core, Logging, Performance
> Affects Versions: 3.0.2
> Environment: Any
> Reporter: Uri Shachar
> Assignee: Leif Hedstrom
> Priority: Minor
> Fix For: 3.1.3
>
> Attachments: diags_cleanup.patch, diags_remove_debugon.patch,
> remove_prefix_arg.patch, remove_prefix_arg_v2.patch,
> remove_prefix_arg_v3.patch
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> The current Diags.h D/EClosure mechanism is obsolete. ATS requires gcc >= 4.1
> for all compilation environments, and it includes variadic argument macro
> support with ##_VA_ARGS_ that deletes the final comma if no arguments are
> provided.
> Removing the added layer should also improve performance when high volume
> debugging is turned on.
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