[jira] [Created] (IO-515) Allow Specifying Initial Buffer Size of DeferredFileOutputStream

["Brett Lounsbury (JIRA)" <ji...@apache.org>]

Brett Lounsbury created IO-515:
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             Summary: Allow Specifying Initial Buffer Size of DeferredFileOutputStream
                 Key: IO-515
                 URL: https://issues.apache.org/jira/browse/IO-515
             Project: Commons IO
          Issue Type: Improvement
          Components: Streams/Writers
            Reporter: Brett Lounsbury


Right now the DeferredFileOutputStream uses a ByteArrayOputStream for its in memory buffer.  It simply does new ByteArrayOutputStream() which initializes the ByteArrayOutputStream's internal buffer to 32B.  In the case of large threshold values for in-memory buffering this can become very inefficient (Requiring 15 array doubling operations to grow to 1MB and producing an extra 1MB of garbage along the way).

By allowing the user to specify the initial buffer size we allow them to tune how many times the array will need to double to something that meets their application's needs.

In our testing we had an application that used a DeferredFileOutputStream to capture incoming data.  Once that data was fully captured it did some fairly CPU intensive processing of the data.  The ByteArrayOutputStream used by DeferredFileOutputStream was using 60% of our host's CPU simply on array copying.



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