Plot gcpacertrace log

pacer.py

# Read gcpacertrace log from stdin and plot pacing.

import sys
import subprocess

gp = subprocess.Popen(["gnuplot", "-persist", "-e", """
set xrange [0:2];
set yrange [0:1];
set xlabel "Heap ratio (h)";
set ylabel "GC CPU (u_a)";
set cblabel "GC cycle";
set arrow 1 from 1,0 to 1,1 nohead ls 0;
load "viridis.pal";
plot "-" with p palette pt 2 title "actual pacing", 0.25/x title "stable trigger" lc 0 lw 2, 0.25 title "goal" ls 0
"""], stdin=subprocess.PIPE).stdin

# Stable trigger:
# 0 = h_g - h_T - u_a / u_g * (h_a - h_T)
# u_a / u_g * (h_a - h_T) = h_g - h_T
# (h_a - h_T) / (h_g - h_T) = u_g / u_a
# h = u_g / u_a

i = 0
for line in sys.stdin:
    if not line.startswith("pacer: H"):
        continue
    v = {}
    for part in line.strip().split()[1:]:
        k, val = part.split("=")
        v[k] = float(val)
    print >> gp, (v["h_a"] - v["h_t"]) / (v["h_g"] - v["h_t"]), v["u_a"], i
    i += 1