ddprof
is in beta. Datadog recommends evaluating the profiler in a non-sensitive environment before deploying in production.
The native profiler for compiled languages (ddprof
) uses OS level APIs to collect profiling data. It is ideally suited for applications written in compiled languages, such as C, C++, or Rust.
Profiles sent from ddprof
show up under the native runtime in the Datadog web app.
Requirements
- Supported operating systems
- Linux (glibc or musl)
- Supported architecture
amd64
or arm64
processors- Serverless
ddprof
is not supported on serverless platforms, such as AWS Lambda.- OS Settings
perf_event_paranoid
kernel setting is 2 or less (see Troubleshooting)- Debugging information
- Symbols should be available. The profiler cannot provide human-readable function names if the symbol table is stripped.
Installation
The profiler can be used either as a standalone executable or as a library. Skip to library installation instructions if you want to use it as a library.
Standalone
Download the latest ddprof
release. For example, here is one way to pull the v0.10.1
release for an amd64
(also known as x86_64
) platform:
curl -L -o ddprof-amd64-linux.tar.xz https://github.com/DataDog/ddprof/releases/download/v0.10.1/ddprof-0.10.1-amd64-linux.tar.xz
tar xvf ddprof-amd64-linux.tar.xz
mv ddprof/bin/ddprof INSTALLATION_TARGET
Where INSTALLATION_TARGET
specifies the location you’d like to store the ddprof
binary. The examples that follow assume INSTALLATION_TARGET
is set to ./ddprof
.
Modify your service invocation to include the profiler. Your usual command is passed as the last arguments to the ddprof
executable.
export DD_ENV=prod
export DD_SERVICE=my-web-app
export DD_VERSION=1.0.3
./ddprof myapp --arg1 --arg2
Note: If you usually launch your application using a shell builtin, for example:
Then you must invoke ddprof
with that builtin instead:
export DD_ENV=prod
export DD_SERVICE=my-web-app
export DD_VERSION=1.0.3
exec ./ddprof myapp --arg1 --arg2
./ddprof --environment prod --service my-web-app --service_version 1.0.3 myapp --arg1 --arg2
Note: If you usually launch your application using a shell builtin, for example:
Then you must invoke ddprof
with that builtin instead:
exec ./ddprof --environment prod --service my-web-app --service_version 1.0.3 myapp --arg1 --arg2
A few minutes after starting your application, your profiles appear on the Datadog APM > Profiler page.
Library
The library exposes a C API.
Download a release of ddprof with library support (v0.8.0 or later) and extract the tarball. For example:
curl -L -o ddprof-amd64-linux.tar.xz https://github.com/DataDog/ddprof/releases/download/v0.10.1/ddprof-0.10.1-amd64-linux.tar.xz
tar xvf ddprof-amd64-linux.tar.xz --directory /tmp
In your code, start the profiler using the ddprof_start_profiling()
interface, defined in the _dd_profiling.h_
header provided by the release. The profiler stops automatically when your program closes. To stop the profiler manually, use ddprof_stop_profiling(ms)
with the ms
parameter indicating the maximum block time of the function in milliseconds. Here is a standalone example (profiler_demo.c
) in C:
#include <stdlib.h>
#include "dd_profiling.h"
int foo(void) {
int n = 0;
for (int i = 0; i < 1000; i++) {
n += 1;
}
return n;
}
int main(void) {
// Initialize and start the Datadog profiler. Uses agent defaults if not
// specified
setenv("DD_ENV", "prod", 1);
setenv("DD_SERVICE", "c_testservice", 1);
setenv("DD_VERSION", "1.0.3", 1);
ddprof_start_profiling();
// Do some work
for (int i = 0; i < 1e6; i++) {
foo();
}
return 0;
}
Pass the include
and lib
subdirectories of the extracted directory to your build system and link against libdd_profiling
. For the above example:
gcc -I/tmp/ddprof/include -L/tmp/ddprof/lib profiler_demo.c -o profiler_demo -ldd_profiling
Deploying the shared library
The shared library must be present in the system’s library search path. Otherwise, the application will fail to start. Using the example from before:
./profiler_demo
./profiler_demo: error while loading shared libraries: libdd_profiling.so: cannot open shared object file: No such file or directory
Avoid this by linking against the static library.
Installing the library
Add the library to the search path by copying it to any existing search directory. To find out what your search directories are, on Linux systems, run:
ld --verbose | grep SEARCH_DIR | tr -s ' ;' \\n
Appending a search directory
Use the LD_LIBRARY_PATH
environment variable to add additional search paths to the runtime linker. For example, using the directory layout from before:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/tmp/ddprof/lib
Configuration
Configuration for the profiler can be set by command line parameters, environment variables, or a combination of both. Whenever both are provided for a given setting, the command line parameter is used.
Environment variable | Long name | Short name | Default | Description |
---|
DD_ENV | environment | E | | The environment name, for example, production . |
DD_SERVICE | service | S | myservice | The service name, for example, web-backend . |
DD_VERSION | service_version | V | | The version of your service. |
DD_AGENT_HOST | host | H | localhost | The hostname for the Datadog agent. |
DD_TRACE_AGENT_PORT | port | P | 8126 | The Datadog agent listening port. |
DD_TRACE_AGENT_URL | url | U | | https://<hostname>:<port> overrides other agent host/port settings. |
DD_TAGS | tags | T | | Tags to apply to an uploaded profile. Must be a list of <key>:<value> pairs separated by commas, such as: layer:api,team:intake . |
DD_PROFILING_NATIVE_NICE | nice | i | | Sets the nice level of the profiler without affecting the instrumented processes. |
DD_PROFILING_NATIVE_SHOW_CONFIG | show_config | c | no | Whether to log profiler configuration parameters. |
DD_PROFILING_NATIVE_LOG_MODE | log_mode | o | stdout | How to emit profiler logs. See the section on logging for details. |
DD_PROFILING_NATIVE_LOG_LEVEL | log_level | l | warn | Determines log verbosity. |
DD_PROFILING_NATIVE_TARGET_PID | pid | p | | Engages pidmode. See the section on pidmode for details. |
DD_PROFILING_NATIVE_GLOBAL | global | g | no | Engages globalmode. See the section on globalmode for details. Overrides –pid. |
When passing command line arguments, precede long names with two dashes and short names with a single dash. For example, --service myservice
and -S myservice
.
The environment
, service
, and service_version
settings are recommended, as they are used by the Profiling UI.
Note: Parameters must be set with a value. For example, to log profiler configuration, you must either set DD_PROFILING_NATIVE_SHOW_CONFIG=yes
or pass --show_config yes
, rather than --show_config
alone. For such arguments, yes
, true
, and enable
may be used interchangeably to enable the setting and no
, false
, and disable
may be used to disable it.
See the full list of parameters or use the command line.
Logging
You can configure logging to one of several endpoints:
stdout
prints the logs to standard output stream (the default).stderr
prints the logs to the standard error stream.syslog
publishes the logs to syslog, attempting to adhere to the specification in RFC 3164.disable
disables the logs entirely.- Any other value is treated as a file path, with a leading
/
designating an absolute path.
Pidmode
When a target PID is given, instrument that PID. When this mode is engaged, any parameter after typical profiler argument processing is ignored. If the owning UID of the target PID and the profiler differ, do one of the following:
- Run the profiler as the root process instead.
- Grant
CAP_PERFMON
to the profiler (Linux v5.8 or later). - Grant
CAP_SYS_ADMIN
to the profiler. - Decrease
perf_event_paranoid
to -1
(consult your distro documentation or system administrator for details).
When a PID is specified in this way, only child processes (both forks and threads) spawned after instrumentation will be followed.
Globalmode
Global mode is intended for debug purposes. When global
is set to yes
, the profiler attempts to profile all the visible processes.
This requires elevated permissions (for example, running as root or granting CAP_PERFMON
, CAP_SYSADMIN
) or setting perf_event_paranoid
to -1
.
./ddprof --environment staging --global yes --service_version full-host-profile
When the profiler is run as the root user, all visible processes are instrumented.
For most configurations, this consists of all processes visible within the profiler’s PID namespace.
Not sure what to do next?
The Getting Started with Profiler guide takes a sample service with a performance problem and shows you how to use Continuous Profiler to understand and fix the problem.
Further Reading
Additional helpful documentation, links, and articles: