Tag:Memory size

  • Flink yarn’s 2 task submission methods


    Introduction to pre job modeEvery time you run a task with flick run, Yan will re apply for Flink cluster resources (jobmanager and taskmanager). After the task is completed, the applied Flink cluster resources will be released. The applied Yan resources are exclusive and do not share resources with other tasks. Run command./bin/flink run -m […]

  • 13、 Linux commands free, top


    Free: the command displays the system memory usage, including physical memory, swap memory, and kernel buffer memory. Syntax format: free [options]      Output content:MemLine (second line) is the memory usage.SwapLine (third line) is the usage of swap space.totalThe column shows the total available physical memory and swap space size of the system.usedColumns show the […]

  • Dotnet c# calls the object assignment of the delegated getinvocationlist


    This article is also called learning performance optimization series with Stephen Toub. This is what I learned from Stephen Toub’s performance optimization for WPF framework. Under the hot path, that is, for frequently called modules, if the delegated getinvocationlist method is called, new array objects of different sizes will be created each time depending on […]

  • How to use MySQL statements for data caching?


    Query cache settings 1) Verify that the server supports query caching show variables like ‘%have_query_cache%’; | Variable_name | Value | | have_query_cache | YES | 2) The query cache is affected by the following three system variable values show variables like ‘query_cache%’; | Variable_name | Value | | query_ cache_ Limit | 1048576 | / […]

  • Redis source code – SDS


    SDS concept: simple dynamic string (SDS) Structure diagram /* *Saves the structure of a string object */ struct sdshdr { //Length of occupied space in buf int len; //Length of free space remaining in buf int free; //Data space char buf[]; }; 3. Difficult code analysis /* *Returns the length of the string actually saved […]

  • [thinking] redis’s key deletion strategy and memory elimination mechanism


    1. Expiration policy of redis 1. Scheduled deletion While setting the expiration time of a key, create a timer for the key to delete the key when the expiration time of the key comesadvantage:Ensure that the memory is released as soon as possibleDisadvantages:1) If there are many expired keys, deleting these keys will take a […]

  • Mongodb memory usage too high


    Official documentation on memory usage https://docs.mongodb.com/v4.2… Starting from mongodb 3.4, the maximum memory occupied is: (computer memory – 1 / 2) Starting in MongoDB 3.4, the default WiredTiger internal cache size is the larger of either: 50% of (RAM – 1 GB), or256 MB. For example, my computer has 16g memory. Mongodb will occupy 7.5GB […]

  • Learn a Linux command every day (112): vmstat


    Command introduction The vmstat command is used for virtual memory statistics. Vmstat reports information about processes, memory, paging, block IO, traps, disks, and CPU activity. Syntax format vmstat [options] [delay [count]] Option description -A # show active inner page -F # displays the total number of processes created since startup -M # display slab information […]

  • What does arraysize mean?


    Send to client in. Another related parameter is SDU (session data unit). The memory size occupied by prefetching in PGA is related to the SDU size. The default is 8K SQL> show arraysize arraysize 15 SQL> create table jason as select * from dba_objects; Table created. SQL> SQL> SQL> select count(1) from dba_objects; COUNT(1) ———- […]

  • Understanding objects in Objective-C


    This article is published to personal blog synchronously. For a better reading experience, please visit here OC is a superset of C language, which provides object-oriented capability. But what is our Object-Oriented Object in OC, or how does it behave in memory? Today, let’s talk about Tao. Object understanding First, solve the problem of what […]

  • What is the method to get the runtime instance in the Java virtual machine?


    The runtime class is used to represent the running state of the Java virtual machine. It is used to encapsulate the Java virtual machine process. Every time you use the “Java” command to start the Java virtual machine, there will be a runtime instance, and there is only one instance. The application will be connected […]

  • Postgre database optimization


    1、 View server configuration 1. View the number of CPUs cat /proc/cpuinfo |grep “physical id” |sort |uniq |wc -l 2. View the number of physical cores of a single CPU cat /proc/cpuinfo |grep “cpu cores” |uniq 3. View logical threads cat /proc/cpuinfo |grep “processor” |wc -l 4. View memory size free 5. View storage size […]