Common technical issues that you could hit during benchmark development.

It doesn’t work. Can you help me?

The first step to identifying any issue is getting a verbose log - setting logging level to TRACE. How exactly you do that depends on the way you deploy Hyperfoil:

  1. If you use CLI and the start-local command, just run it as start-local -l TRACE which sets the default logging level. You’ll find the log in /tmp/hyperfoil.local.log by default.
  2. If you run Hyperfoil manually in standalone mode (non-clustered) the agent will run in the same JVM as the controller. You need to add -Dlog4j.configurationFile=file:///path/to/log4j2-trace.xml option when starting standalone.sh. If you start Hyperfoil through Ansible the same is set using hyperfoil_log_config variable.
  3. If you run Hyperfoil in clustered mode, the failing code is probably in the agents. You need to pass the logging settings to agents using the deployer; with SSH deployer you need to add -Dlog4j.configurationFile=file:///path/to/log4j2-trace.xml to the extras property, in Kubernetes/Openshift there is the log option that lets you set the logging configuration through a config-map.

An example of Log4j2 configuration file with TRACE logging on is here:

<?xml version="1.0" encoding="UTF-8"?>
      <Console name="CONSOLE" target="SYSTEM_OUT">
         <PatternLayout pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %m%n"/>
      <Root level="TRACE">
         <AppenderRef ref="CONSOLE"/>

TRACE-level logging can be very verbose to a point where it will pose a bottleneck. It’s recommended to isolate your problem at lower request rate if that’s possible.

If you need to print variable values for debugging, check out log step.

My phase fails with SLA failure ‘Progress was blocked waiting for a free connection. Hint: increase http.sharedConnections.’

By default Hyperfoil uses single connection to each HTTP(s) host; the default is set so low to force you thinking about connection limits early during test development. If you don’t override this value as in:

  host: http://hyperfoil.io
  sharedConnections: 1000

you get the error above, as the default SLA does not allow a session (virtual user) to be blocked due to not being able to acquire a connection from the connection pool immediatelly. If you can’t increase number of connections (or use HTTP2 that allows multiple requests to multiplex within single connection), you can set

- httpRequest:
    - blockedRatio: 1000 # any value big enough

on each request to drop the default SLA. The blockedRatio value is a threshold ratio between time spent waiting for a free connection and waiting for the response.

You could also wonder why the sessions are missing a connection when the scenario should guarantee there’s always a free connection e.g. when using always phase type with same number of users and connections. However this may not hold when the connection is closed (either explicitly or after receiving a 5xx response) - while Hyperfoil starts replacing that connection immediatelly it takes a moment. If you expects connections to be closed add a few (10%) extra connections. Another reason could be poor balancing of connections and sessions to threads (should be gone in version 0.8).

When I set ‘Host’ header for HTTP request I get warnings

Hyperfoil automatically inserts the ‘Host’ header to each request and when you try to override that for certain request it emits a warning:

Setting `host` header explicitly is not recommended. Use the HTTP host and adjust actual target using `addresses` property.

With this warning on we don’t inject the header as it might be intended, e.g. when the target server does not parse headers in a case-sensitive way (as it should!) and you have to use certain case. However, if you want to run your requests to a different IP than the host resolves to (e.g. hit with Host: example.com) you should rather use

  host: http://hyperfoil.io

When I use a session variable I am seeing the error “Variable foo is not set!”

in-vm: Variable foo is not set!

On occasion a scenario step has been seen to execute out of sequence. To ensure the variable is set beforehand use initialSequences with the step that populates the variable.


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