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Bug 353558 - StreamBufferBase allocates 4k buffers even when reading 1 byte sources
Summary: StreamBufferBase allocates 4k buffers even when reading 1 byte sources
Status: RESOLVED FIXED
Alias: None
Product: CDT
Classification: Tools
Component: cdt-debug-edc (show other bugs)
Version: 8.0   Edit
Hardware: All All
: P3 normal (vote)
Target Milestone: ---   Edit
Assignee: Ken Ryall CLA
QA Contact: Ken Ryall CLA
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-08-02 06:31 EDT by Daniel Thomas CLA
Modified: 2012-05-22 20:33 EDT (History)
3 users (show)

See Also:

Attachments
Patch to fix buffer size to smallest power of 2 large enough if 4096 too high (1.73 KB, patch)
2011-08-02 06:32 EDT, Daniel Thomas CLA 		cdtdoug: iplog+
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Description Daniel Thomas CLA 2011-08-02 06:31:10 EDT 
Build Identifier: I20110613-1736

org.eclipse.cdt.debug.edc.internal.StreamBufferBase is an abstract class used by MemoryStreamBuffer among others. It allocates BUFFER_SIZE = 4096 bytes for use as a buffer for reading whatever underlying source that its children are wrapping. However in many cases (particularly for MemoryStreamBuffer) what is being buffered is much smaller than 4096 bytes, for example 1 byte. Hence this behavior results in excessive memory usage.

The patch to fix this more than halves memory consumption under some workloads.

Reproducible: Always

Steps to Reproduce:
1. Analyze something sufficiently well that the whole executable (or close to it) is read in.
2. Use -Xmx368m -XX:+HeapDumpOnOutOfMemoryError or similar to cause a heap dump to occur when it uses lots of memory
3. Use MemoryAnalyzer to analyze where all the memory is going (this may take some time)
Comment 1 Daniel Thomas CLA 2011-08-02 06:32:49 EDT 
Created attachment 200697 [details]
Patch to fix buffer size to smallest power of 2 large enough if 4096 too high
Comment 2 Kirk Beitz CLA 2011-08-04 21:18:53 EDT 
patch applied and nominally tested locally; awaiting final review and final merge to eclipse edc git repository by ken ryall.