- C++ 71.2%
- Shell 10.2%
- Python 7.8%
- C 6.8%
- M4 2.6%
- Other 1.3%
b46f9528eb
Observed issue
==============
The notification tests (test_notification_multi_app,
test_notif_ust_buffer_usage) occasionally hang on CI
Cause
=====
The consumer pause testpoint reads from a named FIFO opened with
O_NONBLOCK. Between test script echo commands, no process has the
FIFO open for writing. Per POSIX, read() on a FIFO with O_NONBLOCK
and no writers returns 0 (EOF), not -1 with errno set to EAGAIN.
After a 0-byte read, errno is unchanged from its previous value.
The testpoint then evaluates:
ret = (errno == EAGAIN) ? 0 : -errno;
If errno happens to be non-zero and not EAGAIN, the testpoint returns a
non-zero value, causing the data thread to exit silently. Without the
data thread, buffers cannot drain and buffer usage notifications are
never produced, hanging the test.
Solution
========
Explicitly handle read() returning 0 (EOF) as a non-error
condition before falling through to the errno check.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Icc574898cc1d86593f7635d9441338528c902840
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| .vscode | ||
| doc | ||
| extras | ||
| include | ||
| LICENSES | ||
| m4 | ||
| src | ||
| tests | ||
| version | ||
| .clang-format | ||
| .clang-format-ignore | ||
| .clang-tidy | ||
| .commit_template | ||
| .commit_template.license | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitignore | ||
| .gitreview | ||
| .lcovrc | ||
| .shellcheckrc | ||
| .travis.yml | ||
| bootstrap | ||
| ChangeLog | ||
| CLAUDE.md | ||
| CodingStyle.md | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| format-cpp | ||
| LICENSE | ||
| Makefile.am | ||
| pre-inst-env.in | ||
| pyproject.toml | ||
| README.adoc | ||
LTTng‑tools is a set of components to control LTTng tracing.
The project includes:
-
The LTTng session daemon.
-
The LTTng consumer daemon.
-
The LTTng relay daemon.
-
liblttng‑ctl, a library with a C API used to communicate with the session daemon.
-
Python 3 bindings of liblttng‑ctl.
-
lttng, a command-line tool over liblttng‑ctl. -
lttng‑crash, a command-line tool to recover and view LTTng 2 trace buffers in the event of a crash.
Required and optional dependencies
You need the following dependencies to build and run the LTTng‑tools components:
-
Linux kernel ≥ 4.4.0
-
Userspace RCU ≥ 0.14.0.
Debian/Ubuntu package:
liburcu‑dev. -
popt ≥ 1.13
Debian/Ubuntu package:
libpopt‑dev. -
Libxml2 ≥ 2.7.6
Debian/Ubuntu package:
libxml2‑dev
The following dependencies are optional:
-
Babeltrace ≥ 2.1: default viewer of the
lttng viewcommand,make checkand tests.Debian/Ubuntu package:
babeltrace2 libbabeltrace2-dev -
LTTng‑UST (same minor version as LTTng‑tools): LTTng user space tracing (applications and libraries).
Debian/Ubuntu package:
liblttng‑ust‑dev -
Python ≥ 3.5:
make checkand tests.Debian/Ubuntu package:
python3 -
SWIG ≥ 2.0 and Python 3 development headers: Python bindings (enabled at build configuration time with the
‑‑enable‑python‑bindingsoption).Debian/Ubuntu packages:
swig2.0andpython3‑dev -
modprobe and/or kmod ≥ 22: automatic LTTng kernel modules loading (kernel tracing).
-
Bash:
make check. -
man(manual pager): viewlttngcommand manual pages with the‑‑helpoption or with thelttng helpcommand.NoteYou can use the build configuration option ‑‑enable‑embedded‑helpto embed the manual pages into thelttng,lttng‑sessiond,lttng‑relayd, andlttng‑crashprograms so that you don’t needmanto view them. -
libpfm ≥ 4.0: perf regression test suite.
Debian/Ubuntu package:
libpfm4-dev -
xxd:
make checkand certain tests.Debian/Ubuntu package:
xxd -
lcov:
make check-code-coverageDebian/Ubuntu package:
lcov
LTTng‑tools supports both the LTTng Linux kernel tracer and LTTng user space tracer sharing the same minor version. While some minor releases do not change the tracer ABIs and could work, no testing is performed to ensure that cross-version compatibility is maintained.
You don’t need to rebuild or modify applications instrumented with older versions of the LTTng‑UST project to make them work with the components of the latest LTTng‑tools release.
See the LTTng Documentation for more information on versioning.
Build from source
Dependencies
You need the following tools to build LTTng‑tools:
-
GNU Autotools (Automake ≥ 1.12, Autoconf ≥ 2.64, and Autoheader ≥ 2.50)
-
GNU Libtool ≥ 2.2
-
Flex ≥ 2.5.35
-
Bison ≥ 2.4
-
pkg‑config or similiar drop-in replacement
To build the LTTng‑tools manual pages:
If you use GNU gold, which is not mandatory:
-
GNU gold ≥ 2.22
|
Note
|
With GNU gold, you might need to add
-L/usr/local/lib to the LDFLAGS environment variable.
|
Build steps
-
If you have the LTTng‑tools Git source, run:
$ ./bootstrap
This script creates the
configurescript. -
$ ./configure
If you want the liblttng‑ctl Python bindings, use the
‑‑enable‑python‑bindingsoption. See also thePYTHONandPYTHON_CONFIGenvironment variables in./configure ‑‑help.If you don’t want to build the manual pages, use the
‑‑disable‑man‑pagesoption.If you want to embed the manual pages into the
lttng,lttng‑sessiond,lttng‑relayd, andlttng‑crashprograms so that you don’t needmanto view them, use the‑‑enable‑embedded‑helpoption.This build configuration script finds LTTng‑UST with pkg‑config: set the
PKG_CONFIG_PATHenvironment variable accordingly if pkg‑config cannot find thelttng‑ustpackage information.See
./configure ‑‑helpfor the complete list of options. -
Build the project:
$ make
-
Install the project:
$ sudo make install $ sudo ldconfig
Tests
To run all the tests:
$ make check
Usage
See the Tracing control section of the LTTng Documentation to learn how to use the LTTng‑tools components.
See also the LTTng manual pages (all section 1 and 8 pages).
As there’s no official liblttng‑ctl Python bindings yet, see
doc/python-howto.txt to understand how to
use them.
Supported versions
The LTTng project supports the last two released stable versions (e.g. stable-2.13 and stable-2.12).
Fixes are backported from the master branch to the last stable version unless those fixes would break the ABI or API. Those fixes may be backported to the second-last stable version, depending on complexity and ABI/API compatibility.
Security fixes are backported from the master branch to both of the last stable version and the second-last stable version.
New features are integrated into the master branch and not backported to the last stable branch.
Community
- Mailing list
- IRC channel
-
#lttngon the OFTC network - Mastodon
- Bug tracker
- GitHub project
- Continuous integration
-
LTTng‑tools’s master build on LTTng’s CI
- Code review
-
lttng‑tools project on LTTng Review
- Contributor’s guide
-
https://github.com/lttng/lttng-tools/blob/master/CONTRIBUTING.md