Label:/** Technology for connection pooling and caching**/var mysql = require (' mysql ');
var pool = Mysql.createpool ({
connectionlimit:2,//connection pool can create a maximum number of connections
host: ',
User: ' Root ',
database: ' Yudi ',
password: ',
queuelimit:8//queue for maximum number of connections, 0 for unlimited.
});
Pool.query (' select * from person ', function (e
Self-written thread pool, self-written Thread Pool
C # I have ThreadPool and Task. Why do I need to write the thread pool? I have never thought about writing a thread pool myself before. I used ThreadPool or Task to write crawlers some time ago. I want to control 10 threads crawling webpages and 10 threads downloading
What is a memory pool(Memory Pool) is a way of allocating memories.A memory pool is a request to allocate a certain number of memory blocks of equal size (in general) to be reserved before actually using memory. When there is a new memory requirement, a portion of the memory block is separated from the memory pool, and
Use the process pool to circumvent Python GIL restrictions, and the pool to circumvent pythongil
Operating System: CentOS7.3.1611 _ x64
Python version: 2.7.5Problem description
Python GIL will affect CPU-intensive programs. If Python is fully used for programming, how can we avoid GIL restrictions?
Solution
Use a process pool in multiple threads to avoid GIL rest
Java constant pool and Java constant poolFor an interview question on the internet, find the output result:
/**
*
*@authorDreamSea2011-11-19
*/
publicclassIntegerTest{
publicstaticvoidmain(String[]args){
objPoolTest();
}
publicstaticvoidobjPoolTest(){
Integeri1=40;
Integeri2=40;
Integeri3=0;
Integeri4=newInteger(40);
Integeri5=newInteger(40);
Integeri6=newInteger(0);
System.out.println("i1=i2\t"+(i1==i2));
Sy
Tomcat has been using COMMONS-DBCP as a connection pool for the previous version of 7.0, but DBCP has been criticised for the following reasons:
DBCP is single-threaded, in order to ensure that the entire connection pool is locked by the line Shuo plenary
DBCP Poor performance
DBCP is too complex, more than 60 classes
DBCP using static interface, compile in JDK 1.6 problem
DBCP Deve
Python: Process pool, python process pool
1. Can a process be opened infinitely?
Processes cannot be opened infinitely. The cpu has 16 cores, which means that 16 tasks can be processed simultaneously. If there are 160 processes, each process
0.01 s for processing, and 160 s for a 16-core processor to process 0.5 processes, because the more processes, the more time required.
2. Process
Python crawler practice (iii) -------- sogou article (IP proxy pool and user proxy pool settings ---- scrapy ),
In learning the scrapy crawler framework, it will certainly involve setting the IP proxy pool and User-Agent pool to avoid anti-crawling of websites.
In the past two days, I watched a video about sogou's arti
Modify the conf/server. xml file
Easy Configuration
Step 1: Open the shared Thread Pool
Name = "Catalina">
Name = "tomcatthreadpool" nameprefix = "Catalina-Exec -"
Maxthreads = "1000" minsparethreads = "50" maxidletime = "600000"/>
Name = "tomcatthreadpool" nameprefix = "Catalina-Exec-" maxthreads = "1000" minsparethreads = "50" maxidletime = "600000"/>Comments before and after the default value NameThe name used to reference this
Database connection pool: (inside put a lot of connection data links, responsible for allocation, management, release database connection, reusable connection, but not new) for data Unified connection to establish a buffer pool, put a certain database connection, use in the buffer pool inside take, and then back to the buffer
The libvirt Storage section is studied. A simple example is used for test and verification:
Import lib1_conn = libvirt. open ('qemu: // system') # conn = libvirt. open ('qemu: // system ') xmldesc = '''
Output result:
virttest1
Delete storage volumes and storage pools
Import lib1_conn = libvirt. open ('qemu: // system') # conn = libvirt. open ('qemu: // system ') ''' Delete pool vol ''' storage _ pool
Recent research on libvirt, storage
Create an iSCSI storage pool
Import lib1_conn = libvirt. open ('qemu: // system') # conn = libvirt. open ('qemu: // system ') /dev/Disk/by-pathxmldesc = '''
Logical concept correspondence:
When a storage pool is created and an iqn In The iSCSI server is used as the device, the iqn can understand a pool, and the Lun in
, get to threading. Thread class namedef add_thread (self):Self.q.put (Threading. Thread) #如果当前线程执行完毕, put the threads back into the queuePoll = MyThread (5) #实例化MyThread类def task (Arg,pool): #想要线程执行的任务Print (ARG) #输出参数Time.sleep (1)Poll.add_thread () #当线程执行完毕重新put线程到队列For I in range: #循环30次t = Poll.get_thread () #t为threading. Threadobj = t (target = task,args= (i,poll)) #让线程执行任务, and pass parametersObj.start () #开始执行Process sharingFrom multiprocessin
PackageCom.chauvet.utils.threadPool;ImportJava.util.concurrent.ExecutorService;Importjava.util.concurrent.Executors;/*** * * Create a thread pool to control the maximum number of concurrent threads, and the excess threads will wait in the queue. * * The size of a fixed-length pool is best set based on system resources. * such as: Runtime.getruntime (). Availableprocessors () (number of processors available
13. submit method of ThreadPoolExecutor thread pool, submit of java Thread Pool
Jdk1.7.0 _ 79
In the previous article ThreadPoolExecutor thread pool Principle and Its execute method, we mentioned the ThreadPoolExecutor principle of the thread pool and Its execute method. This article analyzes ThreadPoolExecutor # submi
Net website error information: Note:An error occurred while executing the current Web request. Check the stack trace information for details about the error and the source of the error in the code.Exception details:System. invalidoperationexception: the timeout has reached. The timeout time has reached, but the connection has not been obtained from the pool. This may occur because all pool connections are i
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