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dtrace-provider - Native DTrace providers for Node.js apps.

This extension allows you to create native DTrace providers for your Node.js applications. That is, to create providers and probes which expose information specific to your application, rather than information about the node runtime.

You could use this to expose high-level information about the inner workings of your application, or to create a specific context in which to look at information from other runtime or system-level providers.

The provider is not created in the usual way, by declaring it and then changing the build process to include it, but instead dynamically at runtime. This is done entirely in-process, and there is no background compiler or dtrace(1) invocation. The process creating the provider need not run as root.


$ npm install dtrace-provider


Here's a simple example of creating a provider:

var d = require('dtrace-provider');

var dtp = d.createDTraceProvider("nodeapp");
dtp.addProbe("probe1", "int", "int");
dtp.addProbe("probe2", "char *");
dtp.enable();"probe1", function() { return [1, 2]; });"probe2", function() { return ["hello, dtrace"]; });

This example creates a provider called "nodeapp", and adds two probes. It then enables the provider, at which point the provider becomes visible to DTrace.

The probes are then fired, which produces this output:

$ sudo dtrace -Z -n 'nodeapp*:::probe1{ trace(arg0); trace(arg1) }'  \
                 -n 'nodeapp*:::probe2{ trace(copyinstr(arg0));  }'
dtrace: description 'nodeapp*:::probe1' matched 0 probes
dtrace: description 'nodeapp*:::probe2' matched 0 probes
CPU     ID                    FUNCTION:NAME
  1 123562                      func:probe1                 1                2
  1 123563                      func:probe2   hello, dtrace                    

Arguments are captured by a callback only executed when the probe is enabled. This means you can do more expensive work to gather arguments.


The nature of this extension means that support must be added for each platform. Right now that support is only in place for OS X, 64 bit and Solaris, 32 bit.


The maximum number of probe arguments is 6. There's scope to increase this, with some extra complexity in the platform-specific code.

The data types supported are "int" and "char *". There's definitely scope to improve this, with more elaborate argument handling.


Performance is not where it should be, most especially the disabled-probe effect. Probes are already using the "is-enabled" feature of DTrace to control execution of the arguments-gathering callback, but too much work needs to be done before that's checked. Improving this may imply changes to the API shown in the example above. Please see for the details.


The source is available at:

For issues, please use the Github issue tracker linked to the repository. Github pull requests are very welcome.


This node extension is derived from the ruby-dtrace gem, via the Perl module Devel::DTrace::Provider, both of which provide the same functionality to those languages.

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