An lldb plugin for Node.js and V8, which enables inspection of JavaScript states for insights into Node.js processes and their core dumps.
npm install llnode
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Node.js v10.x+ C++ plugin for the LLDB debugger.
The llnode plugin adds the ability to inspect JavaScript stack frames, objects,
source code and more to the standard C/C++ debugging facilities when working
with Node.js processes or core dumps in LLDB.
https://asciinema.org/a/29589
Start an LLDB session with the llnode plugin automatically loaded:
``bashwhich node
npm install -g llnode
llnode -c /path/to/core/dump`
- Never install llnode with sudo as it can easily lead to errors during
installation and execution.
- For more details on starting llnode see the Usage section.
- To get started with the llnode commands see the Commands section.
llnode only supports currently active Node.js versions installed via officialsudo
channels. We recommend installing Node.js with nvm
as it allows users to install global packages without by default, and
it always installs the official executables from https://nodejs.org.
**Do not install Node.js from the default Ubuntu/Debian apt repositories (or from
the default repositories of other Linux distributions), llnode is not compatible
with Node.js installed that way**. If you still want to install Node.js via
apt-get, take a look at
nodesource/distributions.
To use llnode you need to have the LLDB debugger installed. The recommended
version is LLDB 3.9 and above.
- OS X/macOS
- You can install Xcode and use the
LLDB that comes with it.
- Optionally, you can install newer versions of lldb using Homebrew with
`bash`
brew update && brew install --with-lldb --with-toolchain llvm
and make sure /usr/local/opt/llvm/bin gets searched before /usr/bin/
on your . llnode will link to the LLDB installation returned byllvm-config
if available.liblldb
- Linux
- You can install the lldb package using the package manager of your
distribution. You may need to install additional packages for
as well.
- For example, on Ubuntu 18.04 you can install the prerequisites with
`bash`
apt-get install lldb-8 liblldb-8-dev
- FreeBSD
`bash`
# Install llvm with lldb and headers
pkg install llvm39
rm -f /usr/bin/lldb
ln -s /usr/local/bin/lldb39 /usr/bin/lldb
- Windows
- You can install a binary distribution of LLVM
directly or using Chocolatey:
`bat`
cinst -y visualstudio2017buildtools visualstudio2017-workload-vctools llvm git
Visual Studio is required for MSBuild and headers when building llnode. Git
is required to download the lldb headers.
- Android / Termux (Experimental)
- Install Termux (https://termux.com)
- Install Termux Packages
- pkg install clang lldb lldb-dev make
- pkg install nodejs-lts nodejs-lts-dev
- To debug:
`
llnode -- /data/data/com.termux/files/usr/bin/node --abort_on_uncaught_exception script.js
(llnode) run
#### Install llnode globally via npm
If you have lldb available on your PATH, simply run:
`bash`
npm install -g llnode
To build llnode against a specific lldb version matching an lldb executable,
use the --lldb_exe npm option. For example, on Linux the executable on thePATH might be lldb-3.9:
`bashwhich lldb-3.9
npm install --lldb_exe= -g llnode`
After installing with npm, llnode should be available on your PATH as a
shortcut for running LLDB with the llnode plugin.
#### Optional: Install with Homebrew (OS X/macOS)
`bash`
brew install llnode
There are several ways to load the llnode plugin:
If you install llnode globally via npm (npm install -g llnode), you can usellnode
the shortcut script. This starts lldb and automatically issuesplugin load
the command. All parameters to the llnode script are passednode_modules/.bin/llnode
directly to lldb. If you it's not a local installation, the shortcut will be in.
To tell LLDB to load llnode automatically regardless of the
version of lldb that you are running, add this line to ~/.lldbinit:
`
plugin load /path/to/the/llnode/plugin
The path to the llnode plugin should be printed when the installation
is finished. On OS X/macOS the plugin is typically
node_modules/llnode/llnode.dylib, on Linux it'snode_modules/llnode/llnode.so.
The llnode plugin can also be manually loaded into LLDB using the
plugin load command within lldb.
It does not matter whether the plugin load command is issued before or after
loading a core dump or attaching to a process.
Similar to the ~/.lldbinit approach, this way LLDB will also load the plugin
automatically on start-up. Doing this may require additional permissions
to be able to copy the plugin library to the system plugin directory.
On Linux, run make install-linux in the project directory, or ifnode_modules/llnode/llnode.so
installing with npm, copy
to or create a link there.
On OS X/macOS, run make install-osx in the project directory, or ifnode_modules/llnode/llnode.dylib
installing with npm, copy
to or create a link there.
To use llnode with a core dump the core dump needs to be loaded into lldb
along with the exact executable that created the core dump. The executable
contains information that lldb and the llnode plugin need to make sense of
the data in the core dump.
To load a core dump when starting llnode use:
`
llnode /path/to/bin/node -c /path/to/core
or to load the core dump after starting lldb:
(llnode) target create /path/to/bin/node -c /path/to/core
To use llnode against a live process:
`
llnode -- /path/to/bin/node script.js
(llnode) run
This is ideal for debugging an npm package with native code.
To debug a Node.js crash on uncaught exception:
llnode -- /path/to/bin/node --abort_on_uncaught_exception script.js
(llnode) run
lldb will stop your process when it crashes. To see where it stopped use the
v8 bt command. See the Commands section below for more commands.
`
(llnode) v8 help
Node.js helpers
Syntax: v8
The following subcommands are supported:
bt -- Show a backtrace with node.js JavaScript functions and their args. An optional argument is accepted; if
that argument is a number, it specifies the number of frames to display. Otherwise all frames will be
dumped.
Syntax: v8 bt [number]
findjsinstances -- List every object with the specified type name.
Use -v or --verbose to display detailed v8 inspect output for each object.v8 inspect
Accepts the same options as
findjsobjects -- List all object types and instance counts grouped by typename and sorted by instance count. Use
-d or --detailed to get an output grouped by type name, properties, and array length, as well as
more information regarding each type.
findrefs -- Finds all the object properties which meet the search criteria.
The default is to list all the object properties that reference the specified value.
Flags:
* -v, --value expr - all properties that refer to the specified JavaScript object (default)
* -n, --name name - all properties with the specified name
* -s, --string string - all properties that refer to the specified JavaScript string value
getactivehandles -- Print all pending handles in the queue. Equivalent to running process._getActiveHandles() on
the living process.
getactiverequests -- Print all pending requests in the queue. Equivalent to running process._getActiveRequests() on
the living process.
inspect -- Print detailed description and contents of the JavaScript value.
Possible flags (all optional):
* -F, --full-string - print whole string without adding ellipsis
* -m, --print-map - print object's map address
* -s, --print-source - print source code for function objects
* -l num, --length num - print maximum of num elements from string/array
Syntax: v8 inspect [flags] expr
nodeinfo -- Print information about Node.js
print -- Print short description of the JavaScript value.
Syntax: v8 print expr
source list -- Print source lines around the currently selected
JavaScript frame.
Syntax: v8 source list [flags]
Flags:
* -l
For more help on any particular subcommand, type 'help
`
The easiest way to build the plugin:
`bashClone this repo
git clone https://github.com/nodejs/llnode.git && cd llnode
To configure the build yourself:
bash
Detect available lldb installation and download headers if necessary
node scripts/configure.js
To build the addon, set the environment variable LLNODE_BUILD_ADDON=true
To configure with the detected lldb installation
node-gyp configure
To configure with a specified path to headers, where
$lldb_include_dir
contains the /.h> headers
node-gyp configure -- -Dlldb_include_dir=/usr/local/Cellar/llvm/5.0.0/include
To configure with a specified path to the libraries, where
contains
or liblldb.dylib
node-gyp configure -- -Dlldb_lib_dir=/usr/lib/llvm-3.9/libBuild the plugin (and the addon if LLNODE_BUILD_ADDON=true)
node-gyp buildMove the built plugin to the project directory
node scripts/cleanup.js
$3
To run the tests, if
is an executable on the PATH:`bash
npm run test-all # Run both addon and plugin tests
npm run test-plugin # Run plugin tests
npm run test-addon # Run addon tests
`If the LLDB executable is named differently, point
to it before running the tests:bash
TEST_LLDB_BINARY=which lldb-4.0 npm run test-all
`$3
*
to see additional debug info from llnode
* TEST_LLNODE_DEBUG=true to see additional debug info coming from the tests
* LLNODE_CORE=/path/to/core/dump LLNODE_NODE_EXE=/path/to/node
to use a prepared core dump instead of generating one on-the-fly when running
the tests.For example, to inspect the process of
, run:`bash
LLNODE_DEBUG=true lldb -- \
node --abort_on_uncaught_exception --expose_externalize_string \
test/fixtures/inspect-scenario.js
(lldb) run
`To debug
with a prepared core dump:`
LLNODE_DEBUG=true TEST_LLNODE_DEBUG=true \
LLNODE_CORE=/path/to/core/dump/of/inspect/scenario.js \
LLNODE_NODE_EXE=/path/to/node \
node test/scan-test.js
This software is licensed under the MIT License.
Copyright Fedor Indutny, 2016.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to permit
persons to whom the Software is furnished to do so, subject to the
following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
USE OR OTHER DEALINGS IN THE SOFTWARE.