MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

jassinm

import os
import ycm_core
from clang_helpers import PrepareClangFlags

# Set this to the absolute path to the folder (NOT the file!) containing the
# compile_commands.json file to use that instead of 'flags'. See here for
# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
# Most projects will NOT need to set this to anything; you can just change the
# 'flags' list of compilation flags. Notice that YCM itself uses that approach.
compilation_database_folder = ''

kayousterhout

Generating Flame Graphs for Apache Spark

Flame graphs are a nifty debugging tool to determine where CPU time is being spent. Using the Java Flight recorder, you can do this for Java processes without adding significant runtime overhead.

When are flame graphs useful?

Shivaram Venkataraman and I have found these flame recordings to be useful for diagnosing coarse-grained performance problems. We started using them at the suggestion of Josh Rosen, who quickly made one for the Spark scheduler when we were talking to him about why the scheduler caps out at a throughput of a few thousand tasks per second. Josh generated a graph similar to the one below, which illustrates that a significant amount of time is spent in serialization (if you click in the top right hand corner and search for "serialize", you can see that 78.6% of the sampled CPU time was spent in serialization). We used this insight to spee