jstat2prom.py

"""
jstat2prom

 Copyright 2017, 2018, 2019, 2020 Signal Media Ltd

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

"""

import subprocess
import time
import re
import shutil

INTERVAL = '15s'
COUNT = "10000"
SLEEP_TIME = 15
PROM_DIR = "/tmp"
METRIC_PREFIX = "jstat"

# List of metrics:
# jvm_mem_heap_used_bytes gauge
# jvm_mem_heap_max_bytes gauge
# jvm_mem_non_heap_used_bytes gauge
# jvm_mem_non_heap_max_bytes gauge
# jvm_mem_pools_young_used_bytes gauge
# jvm_mem_pools_young_max_bytes gauge
# jvm_mem_pools_old_used_bytes gauge
# jvm_mem_pools_old_max_bytes gauge
# jvm_gc_collectors_young_collection_count counter
# jvm_gc_collectors_young_collection_time_seconds gauge
# jvm_gc_collectors_old_collection_count counter
# jvm_gc_collectors_old_collection_time_seconds gauge
# jvm_gc_collectors_concurrent_collection_count counter
# jvm_gc_collectors_concurrent_collection_time_seconds gauge


def get_pid():
    try:
        return subprocess.check_output(
            ['pgrep', '-n', 'java'],
            stderr=subprocess.STDOUT).decode('ascii').rstrip()
    except subprocess.CalledProcessError:
        return None


def write_to_prom(metrics):
    data = ""
    for k, v in metrics.iteritems():
        if METRIC_PREFIX:
            k = METRIC_PREFIX + "_" + k
            data += "# HELP " + k + "\n"
        if "_count" in k:
            data += "# TYPE " + k + " counter\n"
        else:
            data += "# TYPE " + k + " gauge\n"
        data += k + " " + str(v) + "\n"
    print data
    file = open(PROM_DIR + '/jstat.tmp', 'w')
    file.write(data)
    file.close()
    shutil.move(PROM_DIR + '/jstat.tmp', PROM_DIR + '/jstat.prom')


def get_metrics(data):
    # https://stackoverflow.com/questions/1262328/how-is-the-java-memory-pool-divided
    # heap = survivor + eden + old
    # non heap = metaspace + codecache (cc)
    # young pool = survivor + eden
    # old pool = tenured
    metrics = {
        'jvm_mem_heap_max_bytes': float(data[0]) + float(data[1])
        + float(data[4]) + float(data[6]),
        'jvm_mem_heap_used_bytes': float(data[2]) + float(data[3])
        + float(data[5]) + float(data[7]),
        'jvm_mem_non_heap_max_bytes': float(data[8]) + float(data[10]),
        'jvm_mem_non_heap_used_bytes': float(data[9]) + float(data[11]),
        'jvm_mem_pools_young_max_bytes': float(data[0]) + float(data[1])
        + float(data[4]),
        'jvm_mem_pools_young_used_bytes': float(data[2]) + float(data[3])
        + float(data[5]),
        'jvm_mem_pools_old_max_bytes': float(data[6]),
        'jvm_mem_pools_old_used_bytes': float(data[7]),
        'jvm_gc_collectors_young_collection_count': data[12],
        'jvm_gc_collectors_young_collection_time_seconds': data[13],
        'jvm_gc_collectors_old_collection_count': data[14],
        'jvm_gc_collectors_old_collection_time_seconds': data[15]
    }

    # Add support for concurrent gc metrics available when using g1gc
    if len(data) >= 18:
        metrics['jvm_gc_collectors_concurrent_collection_count'] = data[16]
        metrics['jvm_gc_collectors_concurrent_collection_time_seconds'] = data[17]

    # Convert kbytes into bytes
    for k, v in metrics.iteritems():
        if "bytes" in k:
            metrics[k] = v * 1024
    return metrics


def read_from_jstat():
    command = ['jstat', '-gc']
    pid = get_pid()
    command.extend((pid, INTERVAL, COUNT))
    if pid:
        print "Running jstat against jvm pid {}. Interval: {}".format(
            pid, INTERVAL)
        try:
            p = subprocess.Popen(
                command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
            while True:
                line = p.stdout.readline()
                data = re.findall(r'\d+\.?\d*', line)
                print data
                if (len(data)) == 16:     # jstat will not show FGC value when
                    data.insert(14, "0")  # there are no old GCs
                if (len(data)) > 16: # Accepting CGC/CGCT but not using it for now (>JDK11)
                    metrics = get_metrics(data)
                    write_to_prom(metrics)
                retcode = p.poll()
                if retcode is not None:
                    print "jstat died. Exiting."
                    time.sleep(SLEEP_TIME)
                    break
        except EnvironmentError as e:
            print "Something bad happened: " + str(e)
            time.sleep(SLEEP_TIME)
            return
    else:
        print "Can't get jvm pid. Sleeping for {} seconds.".format(
            str(SLEEP_TIME))
        time.sleep(SLEEP_TIME)


if __name__ == '__main__':
    while True:
        read_from_jstat()