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#!/usr/bin/python
#
# mysqld_qslower MySQL server queries slower than a threshold.
# For Linux, uses BCC, BPF. Embedded C.
#
# USAGE: mysqld_qslower PID [min_ms]
#
# By default, a threshold of 1.0 ms is used. Set this to 0 ms to trace all
# queries (verbose).
#
# This uses USDT probes, and needs a MySQL server with -DENABLE_DTRACE=1.
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 30-Jul-2016 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF, USDT
import sys
import ctypes as ct
# arguments
def usage():
print("USAGE: mysqld_latency PID [min_ms]")
exit()
if len(sys.argv) < 2:
usage()
if sys.argv[1][0:1] == "-":
usage()
pid = int(sys.argv[1])
min_ns = 1 * 1000000
min_ms_text = 1
if len(sys.argv) == 3:
min_ns = float(sys.argv[2]) * 1000000
min_ms_text = sys.argv[2]
debug = 0
QUERY_MAX = 128
# load BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#define QUERY_MAX """ + str(QUERY_MAX) + """
struct start_t {
u64 ts;
char *query;
};
struct data_t {
u64 pid;
u64 ts;
u64 delta;
char query[QUERY_MAX];
};
BPF_HASH(start_tmp, u32, struct start_t);
BPF_PERF_OUTPUT(events);
int do_start(struct pt_regs *ctx) {
u32 pid = bpf_get_current_pid_tgid();
struct start_t start = {};
start.ts = bpf_ktime_get_ns();
bpf_usdt_readarg(1, ctx, &start.query);
start_tmp.update(&pid, &start);
return 0;
};
int do_done(struct pt_regs *ctx) {
u32 pid = bpf_get_current_pid_tgid();
struct start_t *sp;
sp = start_tmp.lookup(&pid);
if (sp == 0) {
// missed tracing start
return 0;
}
// check if query exceeded our threshold
u64 delta = bpf_ktime_get_ns() - sp->ts;
if (delta >= """ + str(min_ns) + """) {
// populate and emit data struct
struct data_t data = {.pid = pid, .ts = sp->ts, .delta = delta};
bpf_probe_read(&data.query, sizeof(data.query), (void *)sp->query);
events.perf_submit(ctx, &data, sizeof(data));
}
start_tmp.delete(&pid);
return 0;
};
"""
# enable USDT probe from given PID
u = USDT(pid=pid)
u.enable_probe(probe="query__start", fn_name="do_start")
u.enable_probe(probe="query__done", fn_name="do_done")
if debug:
print(u.get_text())
print(bpf_text)
# initialize BPF
b = BPF(text=bpf_text, usdt_contexts=[u])
# header
print("Tracing MySQL server queries for PID %d slower than %s ms..." % (pid,
min_ms_text))
print("%-14s %-6s %8s %s" % ("TIME(s)", "PID", "MS", "QUERY"))
class Data(ct.Structure):
_fields_ = [
("pid", ct.c_ulonglong),
("ts", ct.c_ulonglong),
("delta", ct.c_ulonglong),
("query", ct.c_char * QUERY_MAX)
]
# process event
start = 0
def print_event(cpu, data, size):
global start
event = ct.cast(data, ct.POINTER(Data)).contents
if start == 0:
start = event.ts
print("%-14.6f %-6d %8.3f %s" % (float(event.ts - start) / 1000000000,
event.pid, float(event.delta) / 1000000, event.query))
# loop with callback to print_event
b["events"].open_perf_buffer(print_event)
while 1:
b.kprobe_poll()