Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>This is how you turn non-blocking mode on for a file in UNIX:</p> <pre><code>fd = os.open("filename", os.O_CREAT | os.O_WRONLY | os.O_NONBLOCK) os.write(fd, "data") os.close(fd) </code></pre> <p>On UNIX, however, <a href="http://www.remlab.net/op/nonblock.shtml" rel="noreferrer">turning on non-blocking mode has no visible effect for regular files</a>! Even though the file is in non-blocking mode, the <code>os.write</code> call won't return immediately, it will sleep until the write is complete. To prove it to yourself experimentally, try this:</p> <pre><code>import os import datetime data = "\n".join("testing\n" * 10 for x in xrange(10000000)) print("Size of data is %d bytes" % len(data)) print("open at %s" % str(datetime.datetime.now())) fd = os.open("filename", os.O_CREAT | os.O_WRONLY | os.O_NONBLOCK) print("write at %s" % str(datetime.datetime.now())) os.write(fd, data) print("close at %s" % str(datetime.datetime.now())) os.close(fd) print("end at %s" % str(datetime.datetime.now())) </code></pre> <p>You'll notice that the <code>os.write</code> call does take several seconds. Even though the call is non-blocking (technically, it's not blocking, it's sleeping), the call is <em>not</em> asynchronous.</p> <hr> <p>AFAIK, there is no way to write to a file asynchronously on Linux or on Windows. You can simulate it, however, using threads. Twisted has a method named <code>deferToThread</code> for this purpose. Here's how you use it:</p> <pre><code>from twisted.internet import threads, reactor data = "\n".join("testing\n" * 10 for x in xrange(10000000)) print("Size of data is %d bytes" % len(data)) def blocking_write(): print("Starting blocking_write") f = open("testing", "w") f.write(data) f.close() print("End of blocking_write") def test_callback(): print("Running test_callback, just for kicks") d = threads.deferToThread(blocking_code) reactor.callWhenRunning(cc) reactor.run() </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POHow to write to a file using non blocking IO?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USFlimm
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow to write to a file using non blocking IO?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COHow would I gain access to the reactor object from within a LineReciver or other such protocol built by a server factory?
      singulars
      1. PO
      1. USSean
 

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