How to estimate the memory usage of HDFS NameNode for a HDFS cluster?

HDFS stores the metadata of files and blocks in the memory of the NameNode. How to estimate the memory usage of HDFS NameNode for a HDFS cluster? Each file and each block has around 150 bytes of metadata on NameNode. So you may do the calculation based on this. For examples, assume block size is […]

How to get the running process’ parent process’ ID in Python?

How to get the running process’ parent process’ ID in Python? In Python, you can get the parent process’ pid by calling os.getppid(): import os ppid = os.getppid() One example: The shell’s pid: $ echo $$ 21779 Start a python REPL and get its parent pid (the shell’s): $ python Python 2.7.5 (default, Nov 6 […]

How to get the running process’ parent process’ ID in C / C++?

How to get the running process’ parent process’ ID in C / C++? In C and C++, you can call the getppid() library function which is a function from the POSIX library. #include <sys/types.h> #include <unistd.h> pid_t getppid(void); getppid() returns the process ID of the parent of the calling process. Example usage: getppid.c #include <stdio.h> […]

How to get the running process’ pid in C / C++?

How to get the running process’ pid in C / C++? In C and C++, you can call the getpid() library function which is a function from the POSIX library. #include <sys/types.h> #include <unistd.h> pid_t getpid(void); getppid() returns the process ID of the calling process. Example usage: getpid.c #include <stdio.h> #include <sys/types.h> #include <unistd.h> int […]