top-threads

#!/bin/bash
# Copyright (c) 2018, WSO2 Inc. (http://wso2.org) All Rights Reserved.
#
# WSO2 Inc. licenses this file to you 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.
#
# ----------------------------------------------------------------------------
# See top CPU consuming Java threads
# ----------------------------------------------------------------------------

pid=$(pgrep -o java || echo "")
number_of_threads=10
save_output=true
output_directory=""
print_stack_traces=false
number_of_lines=3

function help() {
    echo ""
    echo "Usage: "
    echo "top-threads [-p <pid>] [-n <number_of_threads>] [-x] [-o <output_directory>] [-t] [-l <number_of_lines>] [-h]"
    echo ""
    echo "-p: The Java Process ID. Default: Oldest Java Application"
    echo "-n: Number of top threads to display. Default: $number_of_threads."
    echo "-x: Do not save thread dump and PS output"
    echo "-o: Output directory to save results. A temp directory is used by default."
    echo "-t: Print stack traces."
    echo "-l: Number of lines to print in stack traces. Works with -t option. Default: $number_of_lines."
    echo "-h: Display this help."
    echo ""
}

while getopts "hn:p:xo:tl:" opts; do
    case $opts in
    h)
        help
        exit 0
        ;;
    n)
        number_of_threads=${OPTARG}
        ;;
    p)
        pid=${OPTARG}
        ;;
    x)
        save_output=false
        ;;
    o)
        output_directory=${OPTARG}
        ;;
    t)
        print_stack_traces=true
        ;;
    l)
        number_of_lines=${OPTARG}
        ;;
    \?)
        help
        exit 1
        ;;
    esac
done

if [[ -z $pid ]]; then
    echo "Please specify the Java Process ID"
    exit 1
fi

if ! kill -0 $pid >/dev/null 2>&1; then
    echo "Please make sure the process exists" >&2
    exit 1
fi

function print_line() {
    printf "%-35s %5s %5s %-15s %-5s %5s %15s %6s %6s\n" "$1" "$2" "$3" "$4" "$5" "$6" "$7" "$8" "$9"
}

function print_header() {
    #Print Header. The "ps" command headers are omitted due to manual sort
    print_line "Name" "%CPU" "%MEM" "Thread Status" "State" "Nice" "CPU Time" "LWP" "NID"
}

function process_line() {
    # Read comma separated values to an array
    IFS=, read -a ps_values <<<"$1"
    tid=${ps_values[5]}
    if [[ $pid == $tid ]]; then
        return 0
    fi
    # Convert TID to hexadecimal
    nid=$(printf '%x' $tid)
    # Get thread dump lines for a specific NID to an array
    # Use while loop to read lines into an array
    declare -a thread_dump_lines
    while IFS= read -r line; do thread_dump_lines+=("$line"); done < <(grep -A 20 nid=0x$nid <(echo "$jstack_output"))
    # Get thread name and NID from the first line
    IFS=, read -a thread_details <<<"$(echo "${thread_dump_lines[0]}" | sed -E 's/"(.+)".*nid=(0x[[:xdigit:]]+).*/"\1",\2/')"
    # Get thread status from the second line
    thread_status=$(echo "${thread_dump_lines[1]}" | sed -E 's/.*java.lang.Thread.State:[[:space:]]+([[:upper:]_]+).*/\1/')

    # Print values
    print_line "${thread_details[0]}" "${ps_values[0]}" "${ps_values[1]}" "$thread_status" \
        "${ps_values[2]}" "${ps_values[3]}" "${ps_values[4]}" "${ps_values[5]}" "${thread_details[1]}"
    if [[ $print_stack_traces == true ]]; then
        max_index=${#thread_dump_lines[@]}
        # Stack trace starts from 3rd line, but show first two lines as well
        line_index=0
        # Use let for arithmetic expressions
        let limit=$number_of_lines+2
        while [[ $line_index -lt $limit && $line_index -lt $max_index ]]; do
            line="${thread_dump_lines[$line_index]}"
            if [[ -z "${line// /}" ]]; then
                break
            else
                echo "$line"
            fi
            let line_index=line_index+1
        done
        echo -ne "\n"
    fi
}

#Get ps output first
#Sort manually. ps --sort works only on processes, not on threads.
#Get only specified number of threads and replace spaces with comma
ps_output=$(ps -p $pid -T -o "%cpu=,%mem=,state=,nice=,cputime=,lwp=,pid=" | sort -nr |
    head -$number_of_threads | sed -E -e 's/^[[:space:]]*//' -e 's/[[:space:]]+/,/g')

#Get thread dump
jstack_output=$(jstack $pid)

top_threads_output=$(
    print_header
    echo "$ps_output" | while read line; do process_line "$line"; done
)

#Print top threads
echo "$top_threads_output"

function print_save_message() {
    printf "%-18s %-50s\n" "$1 saved:" "$2"
}

if [[ $save_output == true ]]; then
    prefix=$(date +%s%3N)
    if [[ -z $output_directory ]]; then
        # Use temp directory
        output_directory=$(mktemp -d /tmp/top-threads.XXXXXX)
    elif [[ ! -d $output_directory ]]; then
        mkdir $output_directory
    fi
    ps_output_file=$output_directory/$prefix-ps.txt
    thread_dump_file=$output_directory/$prefix-thread-dump.txt
    top_threads_output_file=$output_directory/$prefix-top-threads.txt
    echo "$ps_output" >$ps_output_file
    print_save_message "PS output" $ps_output_file
    echo "$jstack_output" >$thread_dump_file
    print_save_message "Thread dump" $thread_dump_file
    echo "$top_threads_output" >$top_threads_output_file
    print_save_message "Top threads" $top_threads_output_file
fi