multicore

问题 I have been learning Python in my spare time for a small amount of time now and I set myself a challenge to build a password cracker for a very specific task, it was to test how effective the security on my ADSL Router was (not very) - using Wireshark I could quite clearly see how it was hashing the password over http and I developed some code to perform a wordlist attack. (I apologise if you think my code is badly written - you would probably be correct!). #!/usr/bin/env python import

问题 Recently, I discussed why there is a volatile mark at seq in Java Actors demo @volatile private var seq = 0L private def nextSeq: Long = { val next = seq seq += 1 next } One answer was that threads can be migrated and variables lost (other cores will have incoherent values in their private caches). But, you not normally mark every variable with volatile to enable multicore execution. So, cores must flush the caches whenever context is switched. But, I cannot find this statement pronounced

问题 So, I'm running this simple program on a 16 core multicore system. I run it by issuing the following. spark-submit --master local[*] pi.py And the code of that program is the following. #"""pi.py""" from pyspark import SparkContext import random N = 12500000 def sample(p): x, y = random.random(), random.random() return 1 if x*x + y*y < 1 else 0 sc = SparkContext("local", "Test App") count = sc.parallelize(xrange(0, N)).map(sample).reduce(lambda a, b: a + b) print "Pi is roughly %f" % (4.0 *

问题 So, I'm running this simple program on a 16 core multicore system. I run it by issuing the following. spark-submit --master local[*] pi.py And the code of that program is the following. #"""pi.py""" from pyspark import SparkContext import random N = 12500000 def sample(p): x, y = random.random(), random.random() return 1 if x*x + y*y < 1 else 0 sc = SparkContext("local", "Test App") count = sc.parallelize(xrange(0, N)).map(sample).reduce(lambda a, b: a + b) print "Pi is roughly %f" % (4.0 *

问题 I'm running a multithreaded java app in Linux RedHat 5.3 on a machine that has 8 cores (2 quad-core cpu's). I want to monitor the cpu usage of each thread, preferably relative to the maximal cpu it can get (a single thread running on 1 of the cores should go up to 100% and not 12.5%). Can I do it with jconsole/visualVM? Is there another (hopefully free) tool? Yoav 回答1: If you don't want to use OS specific functions like traversing the /proc directory, you can usually get the values you're

问题 I'm running a multithreaded java app in Linux RedHat 5.3 on a machine that has 8 cores (2 quad-core cpu's). I want to monitor the cpu usage of each thread, preferably relative to the maximal cpu it can get (a single thread running on 1 of the cores should go up to 100% and not 12.5%). Can I do it with jconsole/visualVM? Is there another (hopefully free) tool? Yoav 回答1: If you don't want to use OS specific functions like traversing the /proc directory, you can usually get the values you're

问题 I'm running a multithreaded java app in Linux RedHat 5.3 on a machine that has 8 cores (2 quad-core cpu's). I want to monitor the cpu usage of each thread, preferably relative to the maximal cpu it can get (a single thread running on 1 of the cores should go up to 100% and not 12.5%). Can I do it with jconsole/visualVM? Is there another (hopefully free) tool? Yoav 回答1: If you don't want to use OS specific functions like traversing the /proc directory, you can usually get the values you're

问题 I recently benchmarked the .NET 4 garbage collector, allocating intensively from several threads. When the allocated values were recorded in an array, I observed no scalability just as I had expected (because the system contends for synchronized access to a shared old generation). However, when the allocated values were immediately discarded, I was horrified to observe no scalability then either! I had expected the temporary case to scale almost linearly because each thread should simply wipe

问题 I know that now that most processors have two or more cores, multicore programming is all the rage. Is there functionality to utilize this in Java? I know that Java has a Thread class, but I also know this was around a long time before multicores became popular. If I can make use of multiple cores in Java, what class/technique would I use? 回答1: Does Java have support for multicore processors/parallel processing? Yes. It also has been a platform for other programming languages where the

问题 I know that now that most processors have two or more cores, multicore programming is all the rage. Is there functionality to utilize this in Java? I know that Java has a Thread class, but I also know this was around a long time before multicores became popular. If I can make use of multiple cores in Java, what class/technique would I use? 回答1: Does Java have support for multicore processors/parallel processing? Yes. It also has been a platform for other programming languages where the