- Latest (GraalVM for JDK 21)
- Dev Build
- GraalVM for JDK 21
- GraalVM for JDK 20
- GraalVM for JDK 17
- GraalVM 22.3
- GraalVM 22.2
- GraalVM 22.1
- GraalVM 22.0
- GraalVM 21.3
- Java Reference
- Java on Truffle
- LLVM Languages Reference
- Python Reference
- Ruby Reference
- Debugging Ruby
- Runtime Configurations
- Using Ruby with GraalVM
- Installing `libssl`
- Installing Make and GCC
- Installing `zlib`
- Migration from JRuby to Ruby
- TruffleRuby Options and Command Line
- Polyglot Programming
- Ruby Managers and Installers
- Standalone Distribution
- Development Tools for Ruby
- Ruby Additional Functionality
- Setting up a UTF-8 Locale
- Reporting Performance Problems
- Optcarrot Example
- R Reference
- WebAssembly Reference
Printing Exceptions #
There are two ways to print exceptions, which can be useful to find the source of an error:
- the standard Ruby
-dflag which prints the
file:linewhere each exception was raised
--backtraces-raisewhich show the full backtrace on each exception raised
Both print all exceptions even if the exceptions are later rescued.
Java exceptions can be printed with
--exceptions-* options for more possibilities.
Printing Stacktraces and Backtraces of a Running Process #
One can send the
SIGQUIT signal to TruffleRuby to make it print the Java stacktraces of all threads.
Ctrl + \ can be used to send
SIGQUIT to the current process in a terminal.
This is useful to debug hangs and deadlocks, or to know what the process is doing.
This works on both TruffleRuby Native and JVM.
SIGALRM to a TruffleRuby process will print the Ruby backtraces of all threads.
Note: Printing the Ruby backtraces of all threads significantly lowers performance, so it should only be used for debugging.
More Information in Backtraces #
TruffleRuby tries to match MRI’s backtrace format as closely as possible. This sometimes means that extra available information is not displayed. When debugging you may want to see this information.
An option to show more information is
--backtraces-interleave-java=true, which shows you the Java methods involved in executing each Ruby method.
When you are interoperating with other languages, including C extensions, backtraces for Java exceptions may be missing information, as the Java frames are gone by the time Ruby has a chance to format them into a backtrace.
Printing Subprocesses #
You can log subprocesses created by TruffleRuby using the option
$ ruby --log-subprocess -e '`ls .`' [ruby] INFO: spawn: ls .
This is not transitive though, unless you set this option in
Printing TruffleRuby Processes and Arguments #
You can log TruffleRuby processes created using the
bin/truffleruby launcher and their arguments with
$ ruby --log-process-args -e 0 [ruby] INFO: new process: truffleruby --log-process-args -e 0
You can set this option in
TRUFFLERUBYOPT to make it apply to TruffleRuby subprocess as well.
Separate log files will be used for different subprocesses running at the same time when using
These log files start with the same path but end with
2, etc suffixes.