I'm new to golang. I was debugging my go application.
While I tried to run "info goroutines", it threw out:
Undefined info command: "goroutines".
Try "help info
What did I miss in my gdb configuration?
The article "Debugging Go Code with GDB" does mention:
(gdb) info goroutines
But only in the context of loading extension scripts for a given binary.
The tool chain uses this to extend GDB with a handful of commands to inspect internals of the runtime code (such as goroutines) and to pretty print the built-in map, slice and channel types.
If you'd like to see how this works, or want to extend it, take a look at src/pkg/runtime/runtime-gdb.py in the Go source distribution.
It depends on some special magic types (hash<T,U>) and variables (runtime.m and runtime.g) that the linker (src/cmd/ld/dwarf.c) ensures are described in the DWARF code.
If you're interested in what the debugging information looks like, run 'objdump -W 6.out' and browse through the .debug_* sections.
So make sure your debug session is run with those extensions activated.
in the gdb session run
source $GOROOT/src/runtime/runtime-gdb.py
where $GOROOT is go lives (see go env | grep ROOT)
you should use https://github.com/go-delve/delve as recommended by golang docs https://golang.org/doc/gdb
Related
How to specify the path of generated debug binary file when debug go-lang in vs-code?
I have tried modify launch.json file but not work.
I can debug go programs well now in vs-code, the only problem is each time i finish debug, a debug binary file was generated under my project directory, like the picture below.
I want to know can i specify the directory of generated debug binary file?
I am on mac screen shot of my problem:
This is followed by vscode-go issue 1345: "Delete binary files created by delve after closing the debug session"
delve is the debugger for Golang, or at least it's the one that the Go extension uses.
When you debug something with delve, it creates a large binary file in the current directory. If you debug a main function (dlv debug), you get 'debug'. If you debug a test function (dlv test), you get 'debug.test'.
In normal delve usage, when you're done, you quit delve. Delve then deletes this file. Apparently VSCode gracelessly terminates (SIGKILL?) delve, which means the file sticks around.
So this is studied, but not yet resolved.
Update July 2018: Ramya Rao adds in this issue:
I finally have an update!
Turns out there is a command called Detach that can be called on the delve server which will result in the required clean up of the debug binary that gets generated.
To get this fix before the next update to the Go extension (which will be either Friday or early next week), please follow the below:
Download https://github.com/Microsoft/vscode-go/blob/master/Go-latest.vsix
Run code --install-extension Go-latest.vsix
If the above fails with Error: end of central directory record signature not found, then clone this repo (vsgo) and use the Go-latest.vsix file from the cloned repo
Reload VS Code
The fix worked for me as long as the program being debugged wasn't spawning processes of its own like a web server for which I have logged an upstream issue with delve.
I'd appreciate it if folks here can give the fix a try and share any feedback.
The change you need to do to provide an output path for the generated debug binary is in the launch.json file.
Use the property output in your debug configuration.
Please don't modify the package.json file.
This debug file was generated by delve when debugging and should be deleted after debugging, this seems to be bug of go extension of vs-code, see the link here
I've installed GnuCOBOL 2.2 on my Ubuntu 17.04 system. I've written a basic hello world program to test the compiler.
1 IDENTIFICATION DIVISION.
2 PROGRAM-ID. HELLO-WORLD.
3 *---------------------------
4 DATA DIVISION.
5 *---------------------------
6 PROCEDURE DIVISION.
7 DISPLAY 'Hello, world!'.
8 STOP RUN.
This program is entitled HelloWorld.cbl. When I compile the program with the command
cobc HelloWorld.cbl
HelloWorld.so is produced. When I attempt to run the compiled program using
cobcrun HelloWorld
I receive the following error:
libcob: entry point 'HelloWorld' not found
Can anyone explain to me what an entry point is in GnuCOBOL, and perhaps suggest a way to fix the problem and successfully execute this COBOL program?
According to the official manual of GNUCOBOL, you should compile your code with:
cobc -x HelloWorld.cbl
then run it with
./HelloWorld
You can also read GNUCOBOL wiki page which contains some exmaples for further information.
P.S. As Simon Sobisch said, If you change your file name to HELLO-WORLD.cbl to match the program ID, the same commands that you have used will be ok:
cobc HELLO-WORLD.cbl
cobcrun HELLO-WORLD
Can anyone explain to me what an entry point is in GnuCOBOL, and perhaps suggest a way to fix the problem and successfully execute this COBOL program?
An entry point is a point where you may enter a shared object (this is actually more C then COBOL).
GnuCOBOL generates entry points for each PROGRAM-ID, FUNCTION-ID and ENTRY. Therefore your entry point is HELLO-WORLD (which likely gets a conversion as - is no valid identifier in ANSI C - you won't have to think about this when CALLing a program as the conversion will be done internal).
Using cobcrun internally does:
search for a shared object (in your case HelloWord), as this is found (because you've generated it) it will be loaded
search for an entry point in all loaded modules - which isn't found
There are three possible options to get this working:
As mentioned in Ho1's answer: use cobc -x, the reason that this works is because you don't generate a shared object at all but a C main which is called directly (= the entry point doesn't apply at all)
preload the shared object and calling the program by its PROGRAM-ID (entry point), either manually with COB_PRE_LOAD=HelloWorld cobcrun HELLO-WORLD or through cobcrun (option available since GnuCOBOL 2.x) cobcrun -M HelloWorld HELLO-WORLD
change the PROGRAM-ID to match the source name (either rename or change the source, I'd do the second: PROGRAM-ID. HelloWorld.)
On my fedora box I have installed a lot of separate debug infos.
sudo dnf debuginfo-install <list of packets>
Now, if I debug some simple code it needs very long until some symbol is displayed or some values are printed. It is quite clear that is absolutly needed to evaluate all the installed symbol files to get all information.
But if I have a problem, say on a lib like goocanvas I only want to have my local debug smbols generated with my own compiled code with -g option and the only the debug infos for goocanvas libs.
How can that kind of selection be achieved? Only by renaming the folder of debug info files and generate a copy of needed ones? Maybe as a symlink? Or is there a common selection option anywhere?
You can skip all debug info from shared libraries and only load goocanvas lib symbols. Here is a sample of how to do it in gdb session:
[ ~]$ gdb -q /your/binary
(gdb) set auto-solib-add off
(gdb) start
Temporary breakpoint 1, 0x000055555564edd0 in main ()
(gdb) sharedlibrary goocanvas
From gdb doc:
If your program uses lots of shared libraries with debug info that
takes large amounts of memory, you can decrease the gdb memory
footprint by preventing it from automatically loading the symbols from
shared libraries. To that end, type set auto-solib-add off before
running the inferior, then load each library whose debug symbols you
do need with sharedlibrary regexp, where regexp is a regular
expression that matches the libraries whose symbols you want to be
loaded.
See also this related question: How to prevent GDB from loading debugging symbol for a (large) library?
My Intent
I have an image generated by BitBake on which I'm interested in changing the window manager to metacity or maybe something similar.
My Process
I've added require recipes-graphics/images/core-image-x11.bb into my core recipe, which provides a simple Matchbox terminal window but seemingly no other functionality. If I add matchbox-desktop and matchbox-session-sato, it adds a bit more usability but not what I'm looking for.
I've included the default package from the metacity_2.34.13.bb recipe from the meta-gnome layer from the OpenEmbedded Metadata Index in the IMAGE_INSTALL variable of my core image. This installs several components including a metacity command in /usr/bin. If I run that command, I get the following message:
GLib-GIO-Message: Using the 'memory' GSettings backend. Your settings will not be saved or shared with other applications
(metacity:1124): GLib-GIO-ERROR **: Settings schema 'org.gnome.metacity' is not installed
Trace/breakpoint trap
I've navigated to /usr/share/glib-2.0/schemas and run glib-compile-schemas ., then run:
startx
metacity --replace
again. Now, the output is:
Window manager error: Unable to open X display
I haven't found a clear solution to this error which applies to my specific situation.
Update (2/29):
I may have now found a solution to this error, using these commands:
X&
export DISPLAY=:0
metacity&
At this point, I seem to be running something on one of my VTs. I can run demos like glxgears in that VT (glxgears is included in the mesa-demos recipe), but I don't know how to actually create a usable environment.
My question(s)
I'm not using much from meta-openembedded/meta-gnome (just metacity) or meta/recipes-gnome (adwaita-icon-theme, gnome-desktop3, gsettings-desktop-schemas and gtk+3), so am I missing some recipe which automates the addition of metacity?
(if not Question 1) How can I solve the error Window manager error: Unable to open X display?
The x11-common recipe adds a X session script that will run /usr/bin/x-session-manager: that is responsible for starting your desktop environment.
The way to implement a new session/DE in OE-Core is to use update-alternatives for "x-session-manager": see the matchbox-session recipe for the default implementation and mini-x-session recipe for an alternative.
mini-x-session might be modifiable for your needs so you don't need to write a new one: A /etc/mini_x/session file like this might do the trick:
# start any apps here, e.g. "my-desktop &"
exec metacity
Going from this (a running window manager) to "usable environment" might still be lots and lots of work, depending on your definition of usable.
I have created an release app with rebar3 (beta-4).
Added some eunit tests and wrote some code.
For now I have to debug one test case to see what I have to add to make the implementation to work properly.
I found some articles about using dbg from Erlang console and I found how to write debug info from Eunit. But I need to get info from code that I have to test (the actual implementation(logic)).
Is there a way to debug Erlang code (actual source code, not the test one) when rebar3 is used with eunit argument?
I'm using tracing in terminal like there: https://aloiroberto.wordpress.com/2009/02/23/tracing-erlang-functions/
One way to do this is use rebar3 to run a shell under the test profile, then start the debugger and set up your breakpoints and such:
$ rebar3 as test shell
...
1> debugger:start().
{ok, <0.67.0>}
This will pop up the debugger GUI. Once the debugger is set up and ready, run your test under eunit:
2> eunit:test(your_test_module,[verbose]).
======================== EUnit ========================
your_test_module: xyz_test_ (module 'your_test_module')...
Assuming you set up a suitable breakpoint in the debugger, this will hit it, but you'll likely run into a problem with this approach: by default, eunit tests time out after 5 seconds, which doesn't give you much time for debugging. You need to specify a longer timeout for your test, which is why the example above shows that what's running is a test fixture named xyz_test_, which wraps the actual test with a long timeout. Such a fixture is pretty simple:
-include_lib("eunit/include/eunit.hrl").
xyz_test_() ->
{timeout,3600,
[fun() -> ?assertMatch(expected_value, my_module:my_fun()), ok end]}.
Here, the actual test is the anonymous function, which matches the return value from my_module:my_fun/0, which for this example represents the business logic under test. This example fixture sets the test timeout to one hour; you can of course set it as needed for your application.