Optimize decorator parsing #458
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Profiling showed that a relatively high percentage of CPU time and memory allocations are coming from decorator parsing. This makes sense, since this parsing is applied to every unified log line which goes through gctoolkit. To speed things up, we: - Fold the tags regex into the broader decorator regex, avoiding the need for a second matcher, and removing the need for an expensive negative lookbehind in the tag pattern - Add a start of line anchor to the decorator regex - Defer sanitization of tags until getTags() is called for the first time To reduce unnecessary memory allocations, match groups are retrieved once and stored in an array. In testing, these optimizations cut the running time of gctoolkit roughly in half.
karianna
previously approved these changes
Oct 19, 2025
parser/src/main/java/com/microsoft/gctoolkit/parser/unified/UnifiedLoggingTokens.java
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parser/src/main/java/com/microsoft/gctoolkit/parser/jvm/Decorators.java
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…ifiedLoggingTokens.java
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this is indeed faster, about twice faster for my use case too. |
karianna
approved these changes
Oct 27, 2025
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@johnoliver can you review as well |
johnoliver
reviewed
Oct 28, 2025
| if ( decoratorMatcher.group(i) != null) | ||
| // Retrieving a group from a matcher calls substring each time | ||
| // Store all the groups in an array ahead of time to avoid paying this cost unnecessarily | ||
| decoratorGroups = new String[11]; |
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new String[decoratorMatcher.groupCount()] might be a bit more robust here
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Profiling showed that a relatively high percentage of CPU time and memory allocations are coming from decorator parsing. This makes sense, since this parsing is applied to every unified log line which goes through gctoolkit.
To speed things up, we:
To reduce unnecessary memory allocations, match groups are retrieved once and stored in an array.
In testing, these optimizations cut the running time of gctoolkit roughly in half.