Logging performance bottleneck in DispatcherServlet / UrlPathHelper [SPR-7269]

[spring-projects-issues]

Kenny MacLeod opened SPR-7269 and commented

DispatcherServlet.getLastModified constructs a new UrlPathHelper object each time it is called, which in turn calls LogFactory.getLog. Considering that DispatcherServlet.getLastModified is on the critical execution path, this adds up to a small but significant performance bottleneck.

From what I can see of UrlPathHelper, it should be threadsafe, and the DispatcherServlet should be able to keep a single instance as an object field, rather than instantiating a new one each time.

---

Affects: 3.0.2

Referenced from: commits eb3a3a6

[spring-projects-issues]

Juergen Hoeller commented

Fortunately we already changed that Log field to static for 3.0.3, so the overhead shouldn't be too bad anymore. We can certainly also use a shared UrlPathHelper in DispatcherServlet. That said - we're only creating UrlPathHelpers for debug logging as far as I can see, i.e. only when debug logging is enabled - so is it really a bottleneck in production?

Juergen

[spring-projects-issues]

Kenny MacLeod commented

Ah yes, I didn't notice the isDebugEnabled() condition. You're quite right, this is only causing me a bottleneck because I was profiling in development, with debug enabled,w hich is rather self-deteating :)

Anyway, the static field in 3.0.3 should achieve the same end result.

Thanks.

[spring-projects-issues]

Juergen Hoeller commented

In any case, we are reusing a shared UrlPathHelper instance in DispatcherServlet now. Makes sense even for debug logging.

Juergen