Servers Performance Monitoring

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Introduction

During a load test, it is important to know the health of the servers loaded. It is also nice to see if you are targeting a cluster if the load is correctly dispatched. To address this, the plugin package now supports server monitoring! Using it, you can monitor CPU, Memory, Swap, Disks I/O and Networks I/O on almost all platforms!

Here is how the plugin looks like. It shows the CPU usage of 4 servers involved in the load test:

Metrics Collected

Since version 0.5.0 the Server Agent tool supports collecting over 75 system metrics. See full list.

How it works

Concept

JMeter cannot retrieve by default server metrics except Tomcat ones. To overcome this situation, we have developed a server agent which will get performance data for JMeter. The agent uses the SIGAR open source library. It is composed of a Java common part and native libraries per OS.

Installation

Server Agent tool detailed description is placed here.

Usage

GUI Mode

In GUI mode, just add the listener, define servers and metric types to monitor, ensure the agent is running at remote server and is not blocked by a firewall, then run the test. The values will be displayed at real time chart.

Non GUI Mode

If you run JMeter in non GUI mode and want to save monitoring data to file, just configure result file saving in GUI as you do with other listeners. After running the test you may load saved file into GUI and see the values timeline.

JMeter Properties

• jmeterPlugin.perfmon.interval - metrics collection interval in milliseconds
• jmeterPlugin.perfmon.useUDP - true/false, enabling UDP connection try after failed TCP connection attempt
• jmeterPlugin.perfmon.label.useHostname - true/false, enable using "short" hostnames, default pattern is ([\w\-]+)\..*
• jmeterPlugin.perfmon.label.useHostname.pattern - string (escaped), regular expression to extract hostname (first group is matched)
• e.g. Default pattern would be: jmeterPlugin.perfmon.label.useHostname.pattern=([\w\-]+)\..*
• e.g. Pattern for EC2 us-east/west subdomain matching: jmeterPlugin.perfmon.label.useHostname.pattern=([\w\-]+\.us-(east|west)-[0-9]).*
• forcePerfmonFile - true/false, enabling it makes JMeter to write JTL file with perfmon metrics in the current directory

Common Considerations

PerfMon Server Agent did support only few metrics in versions up to 0.4.2. The old agent still supported in PerfMon Metrics Collector version 0.5.0+. However, version 0.5.0 ships new ServerAgent which provide over 75 separate metrics, support per-process CPU and Memory metrics and even custom metrics for measuring whatever you want: file sizes, database row counts, Java heap sizes and garbage collections.

Specifying Metric Params

PerfMon Metrics Collector has special "Metric Parameter" column, where user can specify metric subtype to collect, specify which process should be monitored (which filesystem, network interface). Metric parameter string may have several parameters inside it, separated with colon `:`. To include colon as a char inside parameter, use backslash escaping `\:`. Make note you cannot use tab characters inside metric parameter string, all tabs will be converted to spaces silently.

Most of the metrics accepts single parameter called 'type'. This parameter specifies which particular number you want to collect. There is default metric type for each metric category that will be collected if no 'type' parameter specified (see lists below, bold first item in each category).

Some metric types are commonly used and considered primary, leaving some rarely used types as additional. Make note that not all metrics available on all platforms, we depend on SIGAR API capabilities here.

Some metrics allow specifying particular object to monitor, you may specify selector parameter to monitor values only for this object:

• name, pid and ptql selectors for processes
• core selector for monitoring specific CPU of multicore systems
• fs selector for filesystems
• iface selector for network interfaces

Make note that metric types are different for per-process and total metrics for CPU and Memory.

Some example metric parameter strings:

``` ### CPU ### combined - measure total CPU usage, equals to 100-idle value core=2:user - measure user process CPU usage for third core in system (core numbering starts at 0) name=java#2:user - will monitor second java process instance for user time spent pid=14523:percent - will monitor process with PID 14523 for total CPU usage percentage name=httpd - omitting metric type will use default 'percent'

### Disk IO ### fs=/home:writes - will monitor /home filesystem for number of write operations

### Network IO ### iface=eth0:tx - will monitor interface eth0 for transmitted packet rate ```