[Mono-bugs] [Bug 71413][Nor] New - Path.GetFullPath is heavy on string allocations

bugzilla-daemon@bugzilla.ximian.com bugzilla-daemon@bugzilla.ximian.com
Tue, 18 Jan 2005 14:22:08 -0500 (EST)

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Changed by joeshaw@novell.com.


--- shadow/71413	2005-01-18 14:22:08.000000000 -0500
+++ shadow/71413.tmp.27756	2005-01-18 14:22:08.000000000 -0500
@@ -0,0 +1,32 @@
+Bug#: 71413
+Product: Mono: Class Libraries
+Version: 1.1
+OS Details: 
+Status: NEW   
+Priority: Normal
+Component: CORLIB
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: joeshaw@novell.com               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+Summary: Path.GetFullPath is heavy on string allocations
+I was using Ben's profiler on beagle and I noticed that we were allocating
+something like 1.1 megs on the heap just from Path.GetFullPath.  The call
+was pretty unnecessary, so simply removing it cut our usage in half, but
+the function itself seems to be quite heavy on the allocations.
+The profiler reported 1.1 MB usage from 10471 calls.  That breaks down to
+about 110 bytes per allocation.  None of the paths involved were longer
+than 80 bytes, and my guess is that the median would be around 20.  Instead
+of splitting up the path and putting it back together, the code could be
+smarter when looking for multiple path separators and . and ..
+Of the 1.1 megs I was able to shave off half of it thanks to
+conditionalizing the call with Path.IsPathRooted, but the other half is
+still there because it's called in the constructor for DirectoryInfo.  Can
+we eliminate that call?  Or at least optimize Path.GetFullPath.