prometheus io

13.1. Blocking and non-blocking io (1) Common blocking functions have wait+pause+sleep functions; Read or write some IO device files (such as serial/mouse/keyboard) can cause blocking The advantage of blocking is that the kernel operating system is simple and beneficial to the full performance of the CPU, and non-blocking IO is required when a thread operates mu

With JavaScript or jquery, you know that JavaScript, especially jquery, has a lot of callback functions, such as Ajax, jquery animations, and so on.$.get (URL, function () {doSomething1 ();//(3)}); (1) doSomething2 (); (2)The code above is jquery Ajax, because Ajax is asynchronous, so in the process of requesting a URL does not block the program, that is, the program runs to (1) does not wait for the results of the AJAX request, continue to execute (2). The second parameter of $.get is a callba

Advantages and disadvantages of blocking and non-blocking Io packages in Java The cornerstone behind NiO design: the reactor model, which is used for event Multi-Channel Separation and dispatching of the architecture model. Reactor: an architecture pattern used for event Multi-Channel Separation and allocation Generally, a file or device specified by a file descriptor can work in two ways: blocking and non-blocking. Blocking means that when you try to

The content of this section: Introduction to I/O Models Blocking I/O (blocking IO) non-blocking I/O (non-blocking IO) multiplexed I/O (IO Multiplexing) Asynchronous I/O (asynchronous I/o) IO Model comparison and analysis Selectors module Introduction to an

is what to do. This can cause a large delay for random reads, bad for database applications, and a good performance for Web servers. This algorithm can also be easily understood to target low-speed disks, because that "guess" is actually intended to reduce the head movement time. This algorithm is therefore more suitable for sequential read and write applications. The kernel parameters that can be used for tuning are Antic_expire, Read_expire, and Write_expire.How to view and set the

Blocking io (blocking IO)In Linux, all sockets are blocking by default, and a typical read operation flow is probably this:When the user process invokes the RECVFROM system call, Kernel begins the first phase of IO: Preparing the data. For network IO, there are times when the data has not arrived at first (for example,

After the organization inspection, I suddenly found myself in the most commonly used Java also have a lot of not understand the place, real for arise a great pity, today deliberately take the time to record these bits, share with you The first batch of knowledge points to be sorted out are as follows: Java IO Inquiry, the entire structure and development of Io, incidentally, accompanied by a compa

File descriptor: A non-negative integer that is the index of the kernel Open file table. Each process has its own file descriptor, the kernel maintains an open file table, a different descriptor points to the kernel File open table, and points to the actual location of the file on the I-node table. Linux System File IO functions ( details can be used in the Linux shell man-a + function name query or query on the Man-online ): Fd=open (Pathname,flags,

Here is the MySQL Ver 14.14 distrib 5.6.19, for Linux (i686) using Editline Wrapper A, MySQL directory files IBDATA1: System table space contains data dictionary, rollback log/undolog, etc. (Insert buffer segment/double write Segment/rollback segment/index segment/dictionary segment/undo segment) Ib_logfile0/ib_logfile1: Transaction log/redolog Mysql-relay-bin: Relay Log Binarylog: Binary Log General_log.log: Regular Log Mysql_error.log: Error Log Slow_query.log: Slow Log . IBD: User t

ObjectiveWith the development and progress of cloud computing technology and services, more and more customers choose to deploy the business to the cloud. However, due to the introduction of the virtualization layer, in the business deployment process often encounter IO problems, often difficult to debug. This article mainly introduces the use of tools such as Perf and Systemtap to help a hosted cloud customer Debug

This article discusses the background of network IO in a Linux environment. The objects and steps involved when IO occurs:For a network IO (here we read for example), it involves two system objects, one that calls the IO process (or thread), and the other is the system kernel (kernel). When a read operation occurs, it

For a network IO (here we read for example), it involves two system objects, one that calls the IO process (or thread), and the other is the system kernel (kernel). When a read operation occurs, the operation goes through two stages: waiting for data preparation (waiting for the database is ready), and copying the data from the kernel to the process (the Copying the data from the kernel to the pro Cess). Co

After learning the Java NIO and IO APIs, a problem flooded into my mind: When should I use IO and when to use NIO? In this article, I'll try to clearly parse the differences between Java NiO and Io, their usage scenarios, and how they affect your code design. The main differences between Java NiO and Io The following

Waiting for data preparation (waiting for theCopy data from the kernel into the process (Copying the data from the kernel-the process)Stevens compared five IO Model in the article:Blocking IOnonblocking IOIO multiplexingSignal Driven IOAsynchronous IOSince signal driven IO is not commonly used in practice, I only refer to the remaining four IO Model.Blocking

1. Questions: recently in the real-time synchronization of the log, before the online is done a single part of the online log stress test, Message Queuing and client, the machine is no problem, but did not think of the second log, the problem came: a machine in the cluster top see the load high, the cluster of machine hardware configuration, the deployment of software are the same, but only this one load problem, the initial speculation that there may be hardware problems. at the same time, we

First, the concept NiO is the new IO, the library is introduced in JDK1.4. NiO and IO have the same effect and purpose, but the implementation is different, NIO is mainly used in blocks, so the efficiency of NIO is much higher than IO. Two sets of NIO are provided in the Java API, one for standard input output NIO and the other for network programming NiO. Ii. t

I reviewed the concepts related to Io, NIO and AIO in the morning and recorded some of these points. from the programming language level BIO | NIO | AIO in the Java perspective, understanding, Linux C also has the concept of AIO (library), these concepts do not know what reason is fired up, here only from the Java perspective. BIO, synchronous blocking Io, simple comprehension: One connect

Classes or interfaces related to Java stream operations:Java Flow class diagram structure:concept and function of flowA stream is a set of sequences of bytes that have a starting point and an end point, a generic or abstract of the data transfer. That is, the transmission of data between the two devices is called the flow, the essence of the flow is data transmission, according to the data transmission characteristics of the stream abstracted into various classes, convenient and more intuitive d

Sometimes when we do maintenance, there will always be similar to the IO is particularly high, but can not be determined to be an IO bottleneck or improper setting of software parameters caused hot disk problems. This is usually the time to know the disk read and write speed, to make the next decision.Here are two methods of testing:(1) using the Hdparm commandThis is a command that is used to obtain the pa

Introduction Java NiO, introduced from JDK1.4, provides a completely different way of working with standard IO. The NIO package (java.nio.*) introduces four key abstract data types that work together to address some of the problems in traditional I/O classes. 1, Buffer: It is a linear table structure that contains data and is used for reading and writing. It also provides a special class for I/O operations for memory-mapped files. 2, Charset: I