pool

问题 This (enormously simplified example) works fine (Python 2.6.6, Debian Squeeze): from multiprocessing import Pool import numpy as np src=None def process(row): return np.sum(src[row]) def main(): global src src=np.ones((100,100)) pool=Pool(processes=16) rows=pool.map(process,range(100)) print rows if __name__ == "__main__": main() however, after years of being taught global state bad!!! , all my instincts are telling me I really really would rather be writing something closer to: from

问题 I have googled a fair bit on this, but not been able to find an exact answer. We are seeing the following errors in our logs: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached. Stack Trace: at MySql.Data.MySqlClient.MySqlPool.GetConnection() at MySql.Data.MySqlClient.MySqlConnection.Open() I can monitor client connections on the MySQL server (and they appear

问题 Why is this code returning "false" instead of "true": package com.company; public class Main { public static void main(String[] args) { String fullName = "Name Lastname"; String name = "Name "; String lastName = "Lastname"; String firstNamePlusLastName = name + lastName; System.out.println(fullName == firstNamePlusLastName); } } If I remember correctly: String firstNamePlusLastName = name + lastName; Should create a String that points to an existing address in memory (String pool) because we

问题 Java has string pool, due to which objects of string class are immutable. But my question stands - What was the need to make String POOL? Why string class was not kept like other class to hold its own values? Is internally JVM need some strings or is this a performance benefit. If yes how? 回答1: A pool is possible because the strings are immutable. But the immutability of the String hasn't been decided only because of this pool. Immutability has numerous other benefits. BTW, a Double is also

问题 In couch base URL, e.g. server:port/pools/default what exactly a couch base pool is. Will it always be default or we can change it. There is some text written there http://www.couchbase.com/docs/couchbase-manual-1.8/couchbase-admin-restapi-key-concepts-resources.html but I cannot really get it 100%. Please anyone can explain. 回答1: A long time ago the Couchbase engineers intended to build out a concept of having pools similar to zfs pools, but for a distributed database. The feature isn't dead

问题 I am looking for a good memory pool implementation in C. it should include the following: Anti fragmentation. Be super fast :) Ability to "bundle" several allocations from different sizes under some identifier and delete all the allocations with the given identifier. Thread safe 回答1: I think the excellent talloc, developed as part of samba might be what you're looking for. The part I find most interesting is that any pointer returned from talloc is a valid memory context. Their example is:

问题 I'm doing research on GenericObjectPool by putting Cipher in pool so it can be reused. GenericObjectPool<Cipher> pool; CipherFactory factory = new CipherFactory(); this.pool = new GenericObjectPool<Cipher>(factory); pool.setMaxTotal(10); pool.setBlockWhenExhausted(true); pool.setMaxWaitMillis(30 * 1000); CipherFactory public class CipherFactory extends BasePooledObjectFactory<Cipher> { private boolean running = false; @Override public Cipher create() throws Exception { return Cipher

问题 Why may this happen? The thing is that monitor object is not null for sure, but still we get this exception quite often: java.lang.IllegalMonitorStateException: (m=null) Failed to get monitor for (tIdx=60) at java.lang.Object.wait(Object.java:474) at ... The code that provokes this is a simple pool solution: public Object takeObject() { Object obj = internalTakeObject(); while (obj == null) { try { available.wait(); } catch (InterruptedException e) { throw new RuntimeException(e); } obj =

问题 According to https://en.wikipedia.org/wiki/Java_class_file#General_layout - the Java constant pool of a class file begins 10 bytes into the file. So far, I've been able to parse everything before that (magic to check if it's a classfile, major/minor versions, constant pool size) but I still don't understand exactly how to parse the constant pool. Like, are there opcodes for specifying method refs and other things? Is there any way I can reference each hex value before text is represented in

问题 I am working on multiprocessing in Python. For example, consider the example given in the Python multiprocessing documentation (I have changed 100 to 1000000 in the example, just to consume more time). When I run this, I do see that Pool() is using all the 4 processes but I don't see each CPU moving upto 100%. How to achieve the usage of each CPU by 100%? from multiprocessing import Pool def f(x): return x*x if __name__ == '__main__': pool = Pool(processes=4) result = pool.map(f, range