| # # ssh to Rackspace 16 vCPU box to perf test lmdb | |
| # # try to do a similar multi-process test to the one at https://github.com/simonhf/sharedhashfile | |
| # # note: could not figure out how to insert more that 70 million keys; other test inserts 100 million keys | |
| # # note: created lmdb hash file on /dev/shm to make it a fairer test | |
| # # note: as you can see below, inserting is extremely slow but lmdb only claims that reading is lighting fast :-) | |
| # # note: the 'mix' 2% update, 98% read test shows that read performance gets bogged down if reading & writing :-( | |
| # # note: not sure if I am using the lmdb API is the optimum way so please forgive me & suggest changes! | |
| # # note: comments to feedback@sharedhashfile.com please | |
| # apt-get update | |
| # apt-get install build-essential |
| #include <stdio.h> | |
| #define TOKENPASTE2(x, y) x ## y | |
| #define TOKENPASTE(x, y) TOKENPASTE2(x, y) | |
| #define FOO TOKENPASTE(var_, __LINE__) | |
| #define BAR __LINE__ | |
| void | |
| main(void) | |
| { |
| MongoDB shell version: 2.6.5 | |
| connecting to: lichess | |
| [ | |
| { | |
| "_id" : "rynNl407", | |
| "p1" : { | |
| "ai" : 8 | |
| }, | |
| "ps" : BinData(0,"AAABAGBgBmYAAAAADQbFAAAADg5gAAAAAOkA4LAAAAA="), | |
| "s" : 31, |
In a project I'm working on I ran into the requirement of having some sort of persistent FIFO buffer or pipe in Linux, i.e. something file-like that could accept writes from a process and persist it to disk until a second process reads (and acknowledges) it. The persistence should be both across process restarts as well as OS restarts.
AFAICT unfortunately in the Linux world such a primitive does not exist (named pipes/FIFOs do not persist
| #include "module.h" | |
| #define MP_SOURCE 1 /* define in a single .c/.cc file */ | |
| #include "msgpuck.h" | |
| // https://tarantool.org/doc/tutorials/c_tutorial.html?highlight=stored%20procedure | |
| // CPATH=/usr/include/tarantool/:/usr/include/ gcc -shared -o hardest.so -fPIC hardest.c | |
| char * key_format = "the quick brown fox jumped over the lazy dog the qu %07u ick brown fox "; | |
| char * field_2 = "'{\"0\":{\"1234567890\": 320, \"1234567890\": 1303}}'"; |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| #include <locale.h> | |
| #include <sys/mman.h> | |
| #include <sys/time.h> | |
| #include <unistd.h> | |
| #include <murmurhash3.h> | |
| // gcc -O3 -I. -o 1-cache-line 1-cache-line.c murmurhash3.c && ./1-cache-line |
| #include <stdio.h> | |
| #include <string.h> | |
| #include <stdint.h> | |
| #include <stdlib.h> | |
| #include <sys/time.h> | |
| #include <locale.h> | |
| #define NUMBYTES (1024*1024*1024) | |
| char bytes[NUMBYTES]; |
| //package com.dnene.josephus; | |
| // $ javac Person.java Chain.java && java Chain | |
| public class Chain | |
| { | |
| private Person first = null; | |
| public Chain(int size) | |
| { |
Let's say you know C and are thinking about learning Golang. Let's also say that you prefer not to use a debugger [1]. This probably means you need to create a debug version of your Golang code. A way to do that is with constant folding [2], for example:
const constDebug = 0
if (1 == constDebug) { debugCode() } // if() compiled away due to constant folding