https://bz.apache.org/bugzilla/show_bug.cgi?id=69659
Bug ID: 69659
Summary: Automatic JSP EL optimization
Product: Tomcat 9
Version: 9.0.98
Hardware: All
OS: All
Status: NEW
Severity: enhancement
Priority: P2
Component: Jasper
Assignee: dev@tomcat.apache.org
Reporter: jeng...@apache.org
Target Milestone: -----
The majority of my application's EL statements contain wasteful empty checks,
added by well-intended engineers who wanted to prevent NPEs. Example:
${not empty availability && not availability.hasError && not empty
availability.primary && availability.primary.type == 'Whatever'}
Since EL inherently handles nulls, those checks are unnecessary, and the
example above could instead be:
${not availability.hasError && availability.primary.type == 'Whatever'}
I modified the existing benchmark TestELParserPerformance to support these two
queries and found the shorter one performs 40% faster. The gains come from
fewer nodes and less reflection, as demonstrated in #69338 and #69381.
Educating our engineers and modifying our entire codebase is impractical, so
I'd like to modify Tomcat to automatically optimize the statements during JSP
code generation. The statements are functionally equivalent so this could be
an always-on feature.
Specifically, I'd create ELOptimizer.optimize(statement) or similar, to be
called by Generator; however I'm unsure of the best way to build that logic. A
single rule like we have here could be implemented a dozen different ways, but
we may want to add more in the future. Is a simple implementation enough for
now or should we invest in an optimizing compiler of some sort?
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