4 ms·

Debuggers are practically useless for me, they aren't complex enough to meet my minimum use-case. If I use a debugger--approximately two hours wasted if I'm com

Debuggers are practically useless for me, they aren't complex enough to meet my minimum use-case. If I use a debugger--approximately two hours wasted if I'm completely unaware where the problem is. If I instead try to spend ten minutes logically explaining the program, usually I fix the problem and also gain a deeper understanding of the mechanics of the program. The program is usually multi-threaded, real-time. A debugger gives you the state of the entire program, and one point in time. A log allows you to focus, which gives you the state you actually care about, at all the points in time where you care about it. The time-evolution of the state of the program is practically the only thing I'm interested in. I find that code that has been written mainly with debuggers is often full of tons of errors, often simple negations which have been worked around an even number of times. Then you're stuck with the debugger, and there's no way to reason about the program. The result is low quality.

pcr910303 7y ago
> If I use a debugger--approximately two hours wasted if I'm completely unaware where the problem is. If I instead try to spend ten minutes logically explaining the program, usually I fix the problem and also gain a deeper understanding of the mechanics of the program. Er.... I’m pretty sure debugger advocates aren’t advocating using debuggers without logical thought. Usually, it’s more about that debugger is a useful tool when one spends three hours logically explaining the problem but can’t figure it out. If you can find all kinds of bugs in ten minutes, then great! You’re officially an endorsed 10x programmer. :-) I can’t, for some bugs, (reproducing bugs in complex programs is a difficult hurdle for me too) so I use a debugger. > I find that code that has been written mainly with debuggers is often full of tons of errors, often simple negations which have been worked around an even number of times. Usually, I find that code that is thoughtfully written and extensively debugged in the debugger is the most robust part of the program, but YYMV.
- solinent 7y ago
  I'm not a 10x programmer, I just spend the time you spend debugging logging. And if I'm correct it's slightly less time than you spend debugging. > Usually, I find that code that is thoughtfully written and extensively debugged in the debugger is the most robust part of the program, but YYMV. Have you ever worked in a code base that is thoughtfully written but not extensively debugged? I'd wager they're pretty rare because of this extensive widespread use of debuggers, but perhaps these code bases are even more robust, since in my experience they're more thoughtfully written. Preconditions and postconditions everywhere!
saagarjha 7y ago
> A debugger gives you the state of the entire program, and one point in time. That’s only if you’re only using the most basic features. A good debugger lets you run dynamic analysis and introspection at the level that static log statements cannot allow.
- unphased 7y ago
  You are referring to the ability to hop around the stack during debugging and inspect variables at will? Whereas with logging you have to log it before you will see it.
apaprocki 7y ago
Discussing your feelings towards debuggers would produce a better discussion if you explained what complexity you find lacking? Nowadays they are incredibly complex pieces of software (e.g., https://rr-project.org https://rr-project.org) if you take the time to learn how to apply what they offer to the kind of software you write. Simple things that people like reasoning about and visualizing with printf() statements can be done in a debugger more easily after using your brain and logic to think about what the issue might be. Think a value got assigned a value it should't have? You add log statements, rebuild, relink, reproduce; or, you could just set a hardware watchpoint to print the backtrace whenever it changes. In my experience people don't reach for the debugger way of doing it simply because it might not be needed all the time and the syntax is forgotten. Diving into `man` or docs is harder than printf(). Use those skills more regularly and/or make a cheatsheet, macros, etc. and it is less of a problem. Debuggers must be used in certain situations. Personally, the canonical example I use is tracking down compiler bugs. I and colleagues have been hit with a number and it would be utterly hopeless to attempt to reason about what is going on without a debugger. (One particular past case that stands out was the compiler, under very certain circumstances, not restoring a register that it was obligated to restore when emitting a catch block. Isolating the root cause and generating a reduced example was loads of fun /s, would not recommend.) Then there's kernels, runtime engines with JIT, diagnosing unreproducible problems in situ where the executable can't be replaced or restarted, and the list goes on...
- jcelerier 7y ago
  > Simple things that people like reasoning about and visualizing with printf() statements can be done in a debugger more easily after using your brain and logic to think about what the issue might be. A big problem that tends to make me sometimes not use debuggers, is that for relatively large software split in many DLLs, adding a printf & rebuilding takes a few seconds, while loading it in gdb or lldb is sometimes north of a minute (or, from my experience with MSVC's "symbol loading", sometimes fifteen minutes).
- solinent 7y ago
  It's more of just a joke--sometimes a simpler solution can do much more than a complex one. Complex solutions aren't necessitated, in fact, I actively avoid them in my product. It's also not for lack of use, I've developed software for more than fifteen years, and I've always had access to some sort of debugger, and I've always used them, just very rarely. >You add log statements, rebuild, relink, reproduce; or, you could just set a hardware watchpoint to print the backtrace whenever it changes. In my experience people don't reach for the debugger way of doing it simply because it might not be needed all the time and the syntax is forgotten. Diving into `man` or docs is harder than printf(). Use those skills more regularly and/or make a cheatsheet, macros, etc. and it is less of a problem. Hardware watch points work horribly for objects, I have to create and maintain views for all the practical objects I use, unless they're very popular libraries like OpenCV. Ultimately, these views could simply be printf or cout statements, maintained with a common function or method defined on all objects. These log statements typically happen right near assert statements, so they can be maintained along with the code. I'll usually use something more sophisticated than simple printf, and I'll have many different types of logs for common debugging cases. They can be enabled or disabled at runtime, so no recompilation needed. They give me access to all the state I could possibly require, and they get committed to the code base. I've had coworkers spend entire days in debuggers (often in groups), where a simple step back and a simple log easily solves the problem. I would use hardware watchpoints if they were standardized across debuggers, but they don't have all the features I need even in the best debuggers, and then I'm still useless on other platforms. Also, I usually need the program to run at near real-time otherwise the bug may not reproduce itself. edit: I should add I do use some of the more advanced debugger features in those rare cases. So debuggers are still necessary, just not in the day-to-day. I should also say I've also worked in environments where the software has to be pretty much bug-free, where small bugs may not be immediately noticeable. So there's a lot of planning, design, even non-formal proofs of correctness happening. If it's allowable for your software to have some bugs, maybe you can take a shortcut with a debugger. Finally, I'm not against all tooling, just debuggers. I use visual profilers all the time.
furyofantares 7y ago
The trap that I’ve seen people get into is thinking they can just blindly step through code and they’ll eventually work out the problem. I think that’s the usage of debuggers that you’re describing. And it’s a bit of a trap, maybe you start out with a targeted breakpoint but then wind up stepping through stuff without any real idea what you’re doing, mostly treading water. Effective use of printf and breakpoints is, IMO, as a tool in logically thinking through the problem. You work out some belief of the problem, you see how this belief being wrong could cause the bug but you can’t see how the belief could be wrong, so you use debugging tools to check your assumption. This is imo the easiest and quickest way to find something surprising. And once the assumption is either validated or invalidated, it’s time to go back to thinking through the problem logically. Personally I prefer printf to breakpoints most of the time, because they leave a trail that I can keep going back to when thinking through the problem logically, and because they build up as I work through a problem. I think printf debugging suffers the “trap” issue less for this reason, but sometimes it’s nice to do a little exploratory debugging once the assumption is invalidated.

pcr910303 7y ago

> If I use a debugger--approximately two hours wasted if I'm completely unaware where the problem is. If I instead try to spend ten minutes logically explaining the program, usually I fix the problem and also gain a deeper understanding of the mechanics of the program. Er.... I’m pretty sure debugger advocates aren’t advocating using debuggers without logical thought. Usually, it’s more about that debugger is a useful tool when one spends three hours logically explaining the problem but can’t figure it out. If you can find all kinds of bugs in ten minutes, then great! You’re officially an endorsed 10x programmer. :-) I can’t, for some bugs, (reproducing bugs in complex programs is a difficult hurdle for me too) so I use a debugger. > I find that code that has been written mainly with debuggers is often full of tons of errors, often simple negations which have been worked around an even number of times. Usually, I find that code that is thoughtfully written and extensively debugged in the debugger is the most robust part of the program, but YYMV.

solinent 7y ago
I'm not a 10x programmer, I just spend the time you spend debugging logging. And if I'm correct it's slightly less time than you spend debugging. > Usually, I find that code that is thoughtfully written and extensively debugged in the debugger is the most robust part of the program, but YYMV. Have you ever worked in a code base that is thoughtfully written but not extensively debugged? I'd wager they're pretty rare because of this extensive widespread use of debuggers, but perhaps these code bases are even more robust, since in my experience they're more thoughtfully written. Preconditions and postconditions everywhere!

saagarjha 7y ago

> A debugger gives you the state of the entire program, and one point in time. That’s only if you’re only using the most basic features. A good debugger lets you run dynamic analysis and introspection at the level that static log statements cannot allow.

unphased 7y ago
You are referring to the ability to hop around the stack during debugging and inspect variables at will? Whereas with logging you have to log it before you will see it.

apaprocki 7y ago

Discussing your feelings towards debuggers would produce a better discussion if you explained what complexity you find lacking? Nowadays they are incredibly complex pieces of software (e.g., https://rr-project.org https://rr-project.org) if you take the time to learn how to apply what they offer to the kind of software you write. Simple things that people like reasoning about and visualizing with printf() statements can be done in a debugger more easily after using your brain and logic to think about what the issue might be. Think a value got assigned a value it should't have? You add log statements, rebuild, relink, reproduce; or, you could just set a hardware watchpoint to print the backtrace whenever it changes. In my experience people don't reach for the debugger way of doing it simply because it might not be needed all the time and the syntax is forgotten. Diving into `man` or docs is harder than printf(). Use those skills more regularly and/or make a cheatsheet, macros, etc. and it is less of a problem. Debuggers must be used in certain situations. Personally, the canonical example I use is tracking down compiler bugs. I and colleagues have been hit with a number and it would be utterly hopeless to attempt to reason about what is going on without a debugger. (One particular past case that stands out was the compiler, under very certain circumstances, not restoring a register that it was obligated to restore when emitting a catch block. Isolating the root cause and generating a reduced example was loads of fun /s, would not recommend.) Then there's kernels, runtime engines with JIT, diagnosing unreproducible problems in situ where the executable can't be replaced or restarted, and the list goes on...

jcelerier 7y ago
> Simple things that people like reasoning about and visualizing with printf() statements can be done in a debugger more easily after using your brain and logic to think about what the issue might be. A big problem that tends to make me sometimes not use debuggers, is that for relatively large software split in many DLLs, adding a printf & rebuilding takes a few seconds, while loading it in gdb or lldb is sometimes north of a minute (or, from my experience with MSVC's "symbol loading", sometimes fifteen minutes).
solinent 7y ago
It's more of just a joke--sometimes a simpler solution can do much more than a complex one. Complex solutions aren't necessitated, in fact, I actively avoid them in my product. It's also not for lack of use, I've developed software for more than fifteen years, and I've always had access to some sort of debugger, and I've always used them, just very rarely. >You add log statements, rebuild, relink, reproduce; or, you could just set a hardware watchpoint to print the backtrace whenever it changes. In my experience people don't reach for the debugger way of doing it simply because it might not be needed all the time and the syntax is forgotten. Diving into `man` or docs is harder than printf(). Use those skills more regularly and/or make a cheatsheet, macros, etc. and it is less of a problem. Hardware watch points work horribly for objects, I have to create and maintain views for all the practical objects I use, unless they're very popular libraries like OpenCV. Ultimately, these views could simply be printf or cout statements, maintained with a common function or method defined on all objects. These log statements typically happen right near assert statements, so they can be maintained along with the code. I'll usually use something more sophisticated than simple printf, and I'll have many different types of logs for common debugging cases. They can be enabled or disabled at runtime, so no recompilation needed. They give me access to all the state I could possibly require, and they get committed to the code base. I've had coworkers spend entire days in debuggers (often in groups), where a simple step back and a simple log easily solves the problem. I would use hardware watchpoints if they were standardized across debuggers, but they don't have all the features I need even in the best debuggers, and then I'm still useless on other platforms. Also, I usually need the program to run at near real-time otherwise the bug may not reproduce itself. edit: I should add I do use some of the more advanced debugger features in those rare cases. So debuggers are still necessary, just not in the day-to-day. I should also say I've also worked in environments where the software has to be pretty much bug-free, where small bugs may not be immediately noticeable. So there's a lot of planning, design, even non-formal proofs of correctness happening. If it's allowable for your software to have some bugs, maybe you can take a shortcut with a debugger. Finally, I'm not against all tooling, just debuggers. I use visual profilers all the time.

furyofantares 7y ago

The trap that I’ve seen people get into is thinking they can just blindly step through code and they’ll eventually work out the problem. I think that’s the usage of debuggers that you’re describing. And it’s a bit of a trap, maybe you start out with a targeted breakpoint but then wind up stepping through stuff without any real idea what you’re doing, mostly treading water. Effective use of printf and breakpoints is, IMO, as a tool in logically thinking through the problem. You work out some belief of the problem, you see how this belief being wrong could cause the bug but you can’t see how the belief could be wrong, so you use debugging tools to check your assumption. This is imo the easiest and quickest way to find something surprising. And once the assumption is either validated or invalidated, it’s time to go back to thinking through the problem logically. Personally I prefer printf to breakpoints most of the time, because they leave a trail that I can keep going back to when thinking through the problem logically, and because they build up as I work through a problem. I think printf debugging suffers the “trap” issue less for this reason, but sometimes it’s nice to do a little exploratory debugging once the assumption is invalidated.