[Java] [Linux] Investigating how the implementation of Java child processes on Linux is realized

I usually use only C / C ++, but I had a chance to worry about the implementation of Java application below when debugging, so make a note. (I haven't touched Java so I'm sorry if I made a mistake)

It seems that ProcessBuilder is used when executing an external program in Java. At that time, a child process is created, and I checked at the source level whether the child process is similar to the child process in Linux.

Someone was investigating something similar, so I quoted halfway.

java.lang.ProcessBuilder.start(…)  //OS common
 → java.lang.ProcessImpl.start(…) //Class for UNIX-like OS(Under the solaris folder)
  → java.lang.UnixProcess.<init> // UNIXProcess.java.linux
--------------------Native code from here(C language) ---------------------
    → Java_java_lang_UNIXProcess_forkAndExec(...)
       (Vfork at the end of this function()Is done)

Quote: Peek inside Process Builder-Apprentice Programming Diary

As above, the C code for each platform is finally called. For the platform abstraction layer of JDK including JNI of Coco et al., See the following articles. C API that abstracts the platform (Java version) --Qiita

With OpenJDK8, the specific sources are as follows. (Linux but the path is included under solaris)

jdk8/jdk8/jdk: d94613ac03d8 src/solaris/native/java/lang/UNIXProcess_md.c

I knew it at the time of the name Java_java_lang_UNIXProcess_forkAndExec, but fork => exec. More specifically, it looks like vfork => ʻexecve` on Linux.

So, in conclusion, I was able to confirm that creating a child process with Java's ProcessBuilder is an implementation of a general process in Linux.

reference

Peek inside ProcessBuilder-Apprentice programming diary jdk8/jdk8/jdk: d94613ac03d8 src/solaris/native/java/lang/UNIXProcess_md.c C API that abstracts the platform (Java version) --Qiita