A glitch is more precisely a software bug that is hard to reproduce. But it has also been used to mean a software bug that is not very serious.
Debugging sucks. But there's also nothing quite that "oh fuck, that's why it doesn't work" moment, which happens after you have examined and placed everything that is relevant to the problem into your brain. You just can't see it coming. It just happens. You just learn what you generally have to look at so it happens faster.
This is a simple hierarchical plaintext notation Ciro Santilli created to explain programs to himself.
It is usuall created by doing searches in an IDE, and then manually selecting the information of interest.
It attempts to capture intuitive information not only of the call graph itself, including callbacks, but of when things get called or not, by the addition of some context code.
For example, consider the following pseudocode:Supose that we are interested in determining what calls
f1() {
}
f2(i) {
if (i > 5) {
f1()
}
}
f3() {
f1()
f2_2()
}
f2_2() {
for (i = 0; i < 10; i++) {
f2(i)
}
}
main() {
f2_2()
f3()
}
f1
.Then a reasonable call hierarchy for
f1
would be:f2(i)
if (i > 5) {
f1()
f2_2()
for (i = 0; i < 10; i++) {
f2(i)
main
f3
f3()
main()
Some general principles:
- start with a regular call tree
- to include context:
- remove any blank lines from the snippet of interest
- add it indented below the function
- and then follow it up with a blank line
- and then finally add any callers at the same indentation level
One of the Holiest age old debugging techniques!
Git has some helpers to help you achieve bisection Nirvana: stackoverflow.com/questions/4713088/how-to-use-git-bisect/22592593#22592593
Obviously not restricted to software engineering alone, and used in all areas of engineering, e.g. Video "Air-tight vs. Vacuum-tight by AlphaPhoenix (2020)" uses it in vacuum engineering.
The cool thing about bisection is that it is a brainless process: unlike when using a debugger, you don't have to understand anything about the system, and it incredibly narrows down the problem cause for you. Not having to think is great!
Nirvana!!!
For JavaScript: stackoverflow.com/questions/17498159/how-to-go-backwards-while-debugging-javascript-in-chrome-sources-debugging/74968631#74968631
What it adds on top of reverse debugging: not only can you go back in time, but you can do it instantaneously.
Or in other words, you can access variables from any point in execution.
TODO implementation? Apparently Pernosco is an attempt at it, though proprietary.
Just add GDB Dashboard, and you're good to go.
The best open source implementation as of 2020 seems to be: Mozilla rr.
- stackoverflow.com/questions/1206872/go-to-previous-line-in-gdb/46996380#46996380
- stackoverflow.com/questions/1470434/how-does-reverse-debugging-work/53063242#53063242
- stackoverflow.com/questions/3649468/setting-breakpoint-in-gdb-where-the-function-returns/46116927#46116927
- stackoverflow.com/questions/27770896/how-to-debug-a-rare-deadlock/50073993#50073993
- stackoverflow.com/questions/522619/how-to-do-bidirectional-or-reverse-debugging-of-programs/50074106#50074106 link only, marked as duplicate of go to previous line
- softwareengineering.stackexchange.com/questions/181527/why-is-reverse-debugging-rarely-used
Proprietary extension to Mozilla rr by rr lead coder Robert O'Callahan et. al, started in 2016 after he quit Mozilla.
TODO what does it add to
rr
?GDB Nirvana?
The musical study of software engineering.
Ciro Santilli is obsessed by those in order to learn any new concept, not just for bug reporting.
This includes to learn more theoretical subjects like physics and mathematics.
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