buffering

I need to create a CSV and upload it to an S3 bucket. Since I'm creating the file on the fly, it would be better if I could write it directly to S3 bucket as it is being created rather than writing the whole file locally, and then uploading the file at the end. Is there a way to do this? My project is in Python and I'm fairly new to the language. Here is what I tried so far: import csv import csv import io import boto from boto.s3.key import Key conn = boto.connect_s3() bucket = conn.get_bucket('dev-vs') k = Key(bucket) k.key = 'foo/foobar' fieldnames = ['first_name', 'last_name'] writer = csv

If print s is replaced by print >>sys.stderr, s then the effect vanishes. import random, sys, time import threading lock = threading.Lock() def echo(s): time.sleep(1e-3*random.random()) # instead of threading.Timer() with lock: print s for c in 'abc': threading.Thread(target=echo, args=(c,)).start() Example # Run until empty line is found: $ while ! python example.py 2>&1|tee out|grep '^$';do echo -n .;done;cat out Output .................... b c a The output should not contain empty lines, but it does. I understand that print is not thread-safe, but I would've thought the lock should help.

I've tried this: main = do hSetBuffering stdin NoBuffering c <- getChar but it waits until the enter is pressed, which is not what I want. I want to read the character immediately after user presses it. I am using ghc v6.12.1 on Windows 7. EDIT: workaround for me was moving from GHC to WinHugs, which supports this correctly. Artelius Might be a bug: http://hackage.haskell.org/trac/ghc/ticket/2189 The following program repeats inputted characters until the escape key is pressed. import IO import Monad import Char main :: IO () main = do hSetBuffering stdin NoBuffering inputLoop inputLoop :: IO

Let's say I want to read a line from a socket, using the standard socket module: def read_line(s): ret = '' while True: c = s.recv(1) if c == '\n' or c == '': break else: ret += c return ret What exactly happens in s.recv(1) ? Will it issue a system call each time? I guess I should add some buffering, anyway: For best match with hardware and network realities, the value of bufsize should be a relatively small power of 2, for example, 4096. http://docs.python.org/library/socket.html#socket.socket.recv But it doesn't seem easy to write efficient and thread-safe buffering. What if I use file

Today in my college a teacher asked me a question. He wrote this code on the paper and said "What will be the output of this code?" use warnings; for (1 .. 20) { print "."; } I found it easy and said that it will loop 20 times and at each iteration it will print a dot (.) and hence total 20 dots will be the output. He said you are right and then he made some changes in the code. The code was: use warnings; for (1 .. 20) { print "."; sleep 1; } He said the what will be the output now? I didn't know about the sleep function, I guessed that at each iteration it will print the dot (.) and then it