4j connections

Label: The current summary of the statement, in view of the data connection is very useful, after writing the program while testing the code side to see the release of database connections to help optimize the analysis of a robust system program. 1.SQL code1.select Count (*) from v$processSelect COUNT (*) from v$process--current number of database connections 2.SQL code1.s

Label:data queries involving two of tables in a database are typically implemented using a connection method. Connections are divided into inner and outer connections. Internal connection: The connection result contains only the rows that meet the join criteria, and the two tables participating in the connection should meet the join criteria. External connection: The result of the join cont

What is persistent connection? In fact, persistent connections are relative to common short connections, that is, to maintain the connection between the client and the server for a long time. The common short connection procedure is as follows: Connection-data transmission-close connection; The persistent connection is usually: Connection-data transmission-keep connection... -Close connection; T

is often used in a point-to-multipoint communication. c/S communication. two, long connection and short connection operation process:the procedure for a short connection is to establish a connection--data transfer--to close the connection ... Establish connection--data transfer--close connection;the operation of the long connection is: Establish a connection-data transmission ... (Keep connected) ... Data transfer--close connectionthree, long connection and the use of short connection time:lo

Today began their own study of Nodejs, see poll, under studyHTTP protocol Description:The HTTP protocol is a request/response paradigm, and each HTTP response is generated by a corresponding HTTP request; The HTTP protocol is stateless, and there is no relationship between multiple HTTP requests.In the case of long-connected applications, the client side generally does not actively shut down their connection between the client and the server if the connection is not closed, there will be a probl

Reprint Address: http://blog.csdn.net/lee576/article/details/3245167Explanation 1The so-called long connection refers to the establishment of a socket connection, regardless of whether or not to remain connected, but less security,The so-called short connection refers to the establishment of a socket connection after the data received after the end of the connection, the general bank used short connectionExplanation 2A long connection is a connection that is maintained in TCP-based communication

Recently, I have seen that a certain architecture uses TCP connections instead of HTTP connections. I realized that I don't know the difference between the two, so I can check the information to complete the knowledge. Refer to the following Blog content: Http://blog.csdn.net/yangzl2008/article/details/7366428 Http://blog.csdn.net/xyylchq/article/details/7660915 Http://blog.csdn.net/xuyide54321/article/deta

1, previous misunderstanding:Previously heard that the HTTP is divided into long connections and short connections, the simple long-term connection is the request can be reused, short connection is only one request, and then the protocol is closed, but in fact this sentence is only half, the HTTP protocol is based on the request/Response mode, as long as the server gave a response, This HTTP connection is o

The following section describes how to view the number of connections in redis and simulate concurrent creation of redis connections in php. I think this is quite good. now I will share it with you and give you a reference. Let's take a look at max_redis.php. /Dev/null ");} Link_redis.php Pconnect ('localhost', 6379); $ redis-> auth ('php001'); sleep (100);?> View current

Cause: A server on the line, has always been a slow access to the situation, click a link for more than 2 seconds to open, according to our estimates of the number of visitors, the server should not respond so slow, so need to address this problem analysis, to solve the site visit too slow. Analysis: 1, first of all, when the page access slows down, use the top command to view the server load situation, found that the load is not high, the initial estimate is not a program problem.2, then, look

The Networkcomms V3 seamlessly supports both TCP and UDP connections.You can easily create these two types of connections// Create a connection information object New ConnectionInfo ("192.168.0.1"10000// Create a TCP connection Connection newtcpconn =// Create a UDP connection Connection newudpconn = Udpconnection.getconnection (Conninfo, Udpoptions.none);A simple usage example: //To specify the processing method for messages with the message type "St

Interpretation 1 Persistent connection means that the connection is maintained no matter whether or not it is used after a socket connection is established, but the security is poor,The so-called short connection means that the connection is closed immediately after the socket connection is established and the data is sent and received. Generally, banks use short connections. Interpretation 2 Persistent connection means to keep the connection in

PrefaceIn database queries, we often use tables to connect queries, and I use these tables to connect to queries myself at work. And just now I haven't figured out what kinds of database table connections are there,These kinds of table connection query way and what difference, it is ashamed! Take this article to bear in mind.Connection Modedatabase table connection query three kinds: inner connection, outer connection, cross connectionSo Let's talk a

The current summary of the statement, in view of the data connection is very useful, after writing the program while testing the code side to see the release of database connections to help optimize the analysis of a robust system program.1.SQL code1.select Count (*) from v$process--Current number of database connectionsSelect COUNT (*) from v$process;2.SQL code1.select value from V$parameter where name = ' processes '--Maximum number of

third step, modify the/etc/sysctl.conf file to add the following line in the file (clear the original contents of the file) (Modify the Network kernel restrictions on TCP connections): Net.ipv4.ip_local_port_range = 1024x768 65535net.core.rmem_max=16777216net.core.wmem_max=16777216net.ipv4.tcp_rmem= 4096 87380 16777216net.ipv4.tcp_wmem=4096 65536 16777216net.ipv4.tcp_fin_timeout = 10net.ipv4.tcp_tw_recycle = 1net.ipv4.tcp_timestamps = 0net.ipv4.

In the development process, the Oracle database is sometimes connected, sometimes not even, prompting the following exception "Ora-12519:tns:no appropriate service handler found resolved", It is possible that the current number of connections on the database has exceeded the maximum value it can handle.– View the current number of connections:Select Count (* from v$process;– Maximum number of connections al

Recently, I encountered an online alarm: a large number of time_wait servers make it unable to establish a new HTTP connection with downstream modules. During the solution, I checked the classic textbooks and technologies.ArticleTo enhance the understanding of TCP network problems. This is recorded as a note.Note: This article mainly introduces the many basic knowledge involved in TCP programming. The solution to the new connection failure caused by time_wait in the actual project will be given