Databases
StackOverflow2013
Postsdbo
POWriting at the end of file
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POWriting at the end of file
    primarykey
    data
    text
    <p>I'm working on a system that requires high file I/O performance (with C#). Basically, I'm filling up large files (~100MB) from the start of the file until the end of the file. Every ~5 seconds I'm adding ~5MB to the file (sequentially from the start of the file), on every bulk I'm flushing the stream. Every few minutes I need to update a structure which I write at the end of the file (some kind of metadata).</p> <p>When flushing each one of the bulks I have no performance issue. However, when updating the metadata at the end of the file I get really low performance. My guess is that when creating the file (which also should be done extra fast), the file doesn't really allocates the entire 100MB on the disk and when I flush the metadata it must allocates all space until the end of file.</p> <p>Guys/Girls, any Idea how I can overcome this problem?</p> <p>Thanks a lot!</p> <p>From comment:</p> <p>In general speaking the code is as follows, first the file is opened: </p> <pre><code>m_Stream = new FileStream(filename, FileMode.CreateNew, FileAccess.Write, FileShare.Write, 8192, false); m_Stream.SetLength(100*1024*1024); </code></pre> <p>Every few seconds I'm writing ~5MB. </p> <pre><code>m_Stream.Seek(m_LastPosition, SeekOrigin.Begin); m_Stream.Write(buffer, 0, buffer.Length); m_Stream.Flush(); m_LastPosition += buffer.Length; // HH: guessed the += m_Stream.Seek(m_MetaDataSize, SeekOrigin.End); m_Stream.Write(metadata, 0, metadata.Length); m_Stream.Flush(); // Takes too long on the first time(~1 sec). </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USHenk Holterman
    1. USLior Ohana
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POWriting at the end of file
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POWriting at the end of file
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POWriting at the end of file
      1. This table or related slice is empty.
      1. VTUpMod
    1. COPlease show us your code.
      singulars
      1. POWriting at the end of file
      1. USSLaks
    2. CODo you mean you pre-allocate the 100MB and _then_ start writing the 5MB chunks starting from position 0? So there are 20 chunks max?
      singulars
      1. POWriting at the end of file
      1. USHenk Holterman
    3. COHi Henk, In general speaking the code is as follows (I'm still trying to understand how to format the code).: First the file is opened: m_Stream = new FileStream(filename, FileMode.CreateNew, FileAccess.Write, FileShare.Write, 8192, false); m_Stream.SetLength(100*1024*1024); Every few seconds I'm writing ~5MB. m_Stream.Seek(m_LastPosition, SeekOrigin.Begin); m_Stream.Write(buffer, 0, buffer.Length); m_Stream.Flush(); m_LastPosition _- buffer.Length; m_Stream.Seek(m_MetaDataSize, SeekOrigin.End); m_Stream.Write(metadata, 0, metadata.Length); m_Stream.Flush(); ==> Too long on first write;
      singulars
      1. POWriting at the end of file
      1. USLior Ohana
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload