fork

redis的淘汰算法持久化

由 有些话、适合烂在心里 提交于 2019-12-09 17:49:06
Redis的淘汰策略 如果你的 Redis 只能存8G数据，你写了11G，那么 Redis 会怎么淘汰那3G数据呢？ redis.conf 中的过期淘汰配置 看下源码的配置 # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory # is reached. You can select among five behaviors: #最大内存策略：当到达最大使用内存时，你可以在下面5种行为中选择，Redis如何选择淘汰数据库键 #当内存不足以容纳新写入数据时 # volatile-lru -> remove the key with an expire set using an LRU algorithm # volatile-lru ：在设置了过期时间的键空间中，移除最近最少使用的key。这种情况一般是把 redis 既当缓存，又做持久化存储的时候才用。 # allkeys-lru -> remove any key according to the LRU algorithm # allkeys-lru ： 移除最近最少使用的key （推荐） # volatile-random -> remove a random key with an expire set # volatile

forking() and CreateProcess()

由 穿精又带淫゛_ 提交于 2019-12-09 16:45:34
问题 Are forking() and CreateProcess(with all required arguments), the same thing for Linux and WinXP, respectively? If they are different, then could someone explain the difference in terms of what happens in each of the two cases? Thanks 回答1: They do different things, and on different systems. CreateProcess is a Windows-only function, while fork is only on POSIX (e.g. Linux and Mac OSX) systems. The fork system call creates a new process and continue execution in both the parent and the child

multi-thread, multi-curl crawler in PHP

由 冷暖自知 提交于 2019-12-09 16:41:26
问题 Hi everyone once again! We need some help to develop and implement a multi-curl functionality into our crawler. We have a huge array of "links to be scanned" and we loop throw them with a Foreach. Let's use some pseudo code to understand the logic: 1) While ($links_to_be_scanned > 0). 2) Foreach ($links_to_be_scanned as $link_to_be_scanned). 3) Scan_the_link() and run some other functions. 4) Extract the new links from the xdom. 5) Push the new links into $links_to_be_scanned. 5) Push the

SpringBoot IDEA 设置热部署

由 不想你离开。 提交于 2019-12-09 16:18:37
1. 给pom.xml中添加依赖 <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional> <scope>true</scope> </dependency> 2. 修改pom.xml中 <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <fork>true</fork> </configuration> </plugin> </plugins> </build> 3. 点开File --> setting --> Build,Execution,Deployment -->Compiler 勾选Build project automatically 第三张图 打开谷歌浏览器，按F12，出来开发者模式，选中Disable cache(while DevTools is open) 来源： CSDN 作者： 入行小菜鸟Mr.L 链接： https://blog

How to find how much memory is shared between forked process with copy-on-write in Linux?

由 跟風遠走 提交于 2019-12-09 16:17:51
问题 If there is a process that reads a big file and saves it in its memory(or just a malloced char*), and that main process is forked, if the child process only reads from that memory(or the char*), according to copy-on-write, the memory where the pointer is saved is not copied, and both parent and child share the same memory until either one of them tries to write on that memory in which case the process makes a copy of the memory and changes that. So my question is if there is a copy-on write

Why does ant.bat not return an error status when run programmatically?

由 筅森魡賤 提交于 2019-12-09 15:53:51
问题 When I run ant from the command-line, if I get a failure, I get a non-zero exit status ($? on UNIX, %ERRORLEVEL% on Windows). But we have a Java program which is running ant (through ProcessBuilder), and when ant fails, on Windows we cannot get the exit status. I just verified this with this simple ant test file: <project name="x" default="a"> <target name="a"> <fail/> </target> </project> On UNIX, running ant prints a failure message, and echoing $? afterward prints 1. On Windows, running

Make children process wait until receiving parent's signal

由 天涯浪子 提交于 2019-12-09 13:54:46
问题 I want to create N children from a parent. I want all the children to start (a function - to measure time) at the same time. So I put the function in a signal handler and when the parent finish creating (fork) all children, it sends the signal (using kill(children_id)) to all children to let make start. The code is below but it doesn't work as expected. Specifically, it forked all children but does not execute function "measure_time" at all. This function does not thing but record execution

fork: close all open sockets

由 这一生的挚爱 提交于 2019-12-09 13:28:18
问题 I am using multiprocessing.Pool.map , which forks the current process. My understanding is that by default, all file descriptors including sockets are copied from the master process when forking. The master process itself is a web server (using cherrypy), so this wreaks havoc with open ports etc. The forked processes are really only doing some CPU-heavy numerical stuff inside one of the libraries that the server is using -- nothing to do with the web/socket part. Is there an easy way to

Calling system() from multithreaded program

由 ╄→гoц情女王★ 提交于 2019-12-09 13:03:30
问题 We are working on a multithreaded memory-consuming application written in C++. We have to execute lots of shellscript/linux commands (and get the return code). After reading that article we clearly understood that it would be a bad idea to use system() in our context. A solution would be to fork after program starts and before creating any threads but the communication with that process may not be easy (socket, pipe ?). The second solution we considered may consist of a dedicated deamon

[APUE]Does parent and child share the same file offset after fork?

由 为君一笑 提交于 2019-12-09 12:56:09
问题 In APUE section 8.3 fork function , about file sharing between parent and child processes, It said: It is important that the parent and the child share the same file offset. And in section 8.9 Race Conditions , there is a example: both parent and child write to a file which is opened before invoking fork function. The program contains a race condition, because the output depends on the order in which the processes are run by the kernel and for how long each process runs. But in my test code,
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