4 ms·
It is to me incredible, how many „developers“, even “10 years senior developers” have no idea how to use a dubugger and or profiler. I’ve even met some that ask
by f1shy 6mo ago
It is to me incredible, how many „developers“, even “10 years senior developers” have no idea how to use a dubugger and or profiler. I’ve even met some that asked “what is a profiler?”
I hope I’m not insulting anybody, but to me is like going to an “experienced mechanic” and they don’t know what a screwdriver is.
- afpx 6mo agoThe last time I interviewed (around 10 years ago) I was surprised when 9 of the 10 senior developers didn't know how many bits were in basic elemetary types. (Then, shortly afterward I also tried to find a new job, realized the entire industry had changed, and was fortunate enough to decide it wasn't worth the trouble.)
- WalterBright 6mo ago> 9 of the 10 senior developers didn't know how many bits were in basic elemetary types That's likely thanks to C which goes to great pains to not specify the size of the basic types. For example, for 64 bit architectures, "long" is 32 bits on the Mac and 64 bits everywhere else. The net result of that is I never use C "long", instead using "int" and "long long". This mess is why D has 32 bit ints and 64 bit longs, whether it's a 32 bit machine or a 64 bit machine. The result was we haven't had porting problems with integer sizes.
- afpx 6mo agoThat's a reasonable answer. But, I meant they seemed to have little understanding or interest. I don't interview much, and I'm probably a poor interviewer. But, I guess I was expecting some discussion.
- WalterBright 6mo agoI ran into some comp sci graduates in the early 80's who did not know what a "register" was. To be fair, though, I come up short on a lot of things comp sci graduates know. It's why Andrei Alexandrescu and I made a good team. I was the engineer, and he the scientist. The yin and the yang, so to speak.
- sas224dbm 6mo agoOooh, saw Andrei's name pop up and remember his books on C++ back in the day .. ran into a systems engineer a while ago that asked why during a tech review asked why some data size wasn't 1000 instead of 1024.. like err ??
- switchbak 6mo agoIt's substantially worse on the JVM. One's intuition from C just fails when you have to think about references vs primitives, and the overhead of those (with or without compressed OOPs). I've met very few folks who understand the overheads involved, and how extreme the benefits can be from avoiding those.
- Quarrelsome 6mo agoConversely I've met many folks who come into managed environments and piss away time trying to wrangle the managed system into how they think it should work, instead of accepting that clever people wrote it and guidelines when followed result in acceptable outcomes. The sort of insane stuff I've seen on the dotnet repo where people are trying to tear apart the entire type system just because they think they've cracked some secret performance code.
- andai 6mo ago>on the dotnet repo You mean the .net compiler/runtime itself? I haven't looked at it, but isn't that the one place you'd expect to see weirdly low-level C# code?
- awesome_dude 6mo agoMy favourite JVM trivia, although I openly admit I don't know if it's still true, is the fact that the size of a boolean is not defined. If you ask a typical grad the size of a bool they will inevitably say one bit, but, CPUs and RAM, etc don't work like that, typically they expect WORD sized chunks of memory - meaning that the boolean size of one but becomes a WORD sized chunk, assuming that it hasn't been packed
- KnuthIsGod 6mo ago". While it represents one bit of information, it is typically implemented as 1 byte in arrays, and often 4 bytes (an int) or more as a standalone variable on the stack "
- gf000 6mo ago
- m463 6mo agoEven more fun is pointers, especially when windows / macos were switching from 32-bits to 64-bits (in different ways).
- WalterBright 6mo agoMicrosoft tried valiantly to make Win16 code portable to Win32, and Win32 to Win64. But it failed miserably, apparently because the programmers had never ported 16 bit C to 32 bit C, etc., and picked all the wrong abstractions.
- AdieuToLogic 6mo ago> Even more fun is pointers, especially when windows / macos were switching from 32-bits to 64-bits (in different ways). And yet even more of a fun time with porting pointer code was going from the various x86 memory models[0] to 32-bit. Depending on the program, the pain was either near, far, or huge... :-D 0 - https://en.wikipedia.org/wiki/X86_memory_models https://en.wikipedia.org/wiki/X86_memory_models
- andai 6mo agoWhy did they design it like that? It must have seemed like a good idea at the time.
- WalterBright 6mo agoC is a portable language, in that programs will likely compile successfully on a different architecture. Unfortunately, that doesn't mean they will run properly, as the semantics are not portable.
- LPisGood 6mo agoSo what’s the point of having portable syntax, but not portable semantics?
- WalterBright 6mo agoC certainly gives the illusion of portability. I recall a fellow who worked on DSP programming, where chars and shorts and ints and longs were all 32 bits. He said C was great because that would compile. I suggested to him that he'd have a hard time finding any existing C code that ran correctly on it. After all, how are you going to write a byte to memory if you've only got 32 bit operations? Anyhow, after 20 years of programming C, I took what I learned and applied it to D. The integral types are specified sizes, and 2's complement. One might ask, what about 16 bit machines? Instead of trying to define how this would work in official D, I suggested a variant of D where the language rules were adapted to 16 bits. This is not objectively worse than what C does, and it works fine, and the advantage is there is no false pretense of portability.
- jandrewrogers 6mo agoIn ancient computing times, which is when C was birthed, the size of integers at the hardware level and their representation was much more diverse than it is today. The register bit-width was almost arbitrary, not the tidy powers of 2 that everyone is accustomed to today. The integer representation wasn't always two's complement in the early days of computing, so you couldn't even assume that. C++ only required integer representations to be two's complement as of C++20, since the last architectures that don't work this way had effectively been dead for decades. In that context, an 'int' was supposed to be the native word size of an integer on a given architecture. A long time ago, 'int' was an abstraction over the dozen different bit-widths used in real hardware. In that context, it was an aid to portability.
- account42 6mo ago> That's likely thanks to C which goes to great pains to not specify the size of the basic types. For example, for 64 bit architectures, "long" is 32 bits on the Mac and 64 bits everywhere else. Don't you mean Windows instead of Mac? Most Unix-like operating systems use LP64 while Windows uses LLP64.
- ekidd 6mo agoI mean, as a senior developer, the number of bits in an "int" is "who the hell knows, because it has changed a bunch of times during my career, and that's what stdint.h is for." And let's not even talk about machines with 32-bit "char" types, which I actually had to program for once. If the number of bits isn't actually included right in the type name, then be very sure you know what you're doing. The senior engineer answer to "How many bits are there in an int?" is "No, stop, put that down before you put your eye out!" Which, to be fair, is the senior engineer answer to a lot of things.
- SAI_Peregrinus 6mo agoHow many bits are in an `int` in C? What do you mean "at least 16", that's ridiculous, nobody would write a language that leaves the number of bits in basic elementary types partially specified‽
- bluGill 6mo agoIt is a good idea - most of the time you don't care, and on slower systems a large int is harmful since the system can't handle that much and it cost performance - go to the faster system with larger ints when you need larger intw.
- estimator7292 6mo agoOn the one hand, in today's world asking how many bits is in an int is exactly as answerable as "how long is a piece of rope" On the other, the right answer is 16 or 32. It's not the correct answer, strictly speaking, but it is the right one.
- jandrewrogers 6mo agoAn 'int' is also 64 bits on some platforms.
- fragmede 6mo agoIt's the wrong question. How many bits is uint64 is a much better question, if we're at a place where that's relevant.
- i_am_a_peasant 6mo agoI had one tell me all ints are 16 bits, and then they said 0xffff is a 32bit number.
- didgetmaster 6mo agoI once interviewed at Microsoft. The hiring manager asked me how I would go about programming a break point if I were writing a debugger. I started to explain how I would have to swap out an instruction to put an INT 3 in the code and then replace it when the breakpoint would hit. He stopped me an said he was just looking to see if I knew what an INT 3 was. He said few engineers he interviewed had any idea.
- rustystump 6mo agoWhat is an int3
- lock1 6mo agoCPU interrupt for breakpoint, https://wiki.osdev.org/Interrupt_Vector_Table https://wiki.osdev.org/Interrupt_Vector_Table
- kitd 6mo agoDid you get the job ... or were you overqualified?
- didgetmaster 6mo agoI guess I was overqualified. Didn't get the job.
- jamesfinlayson 6mo agoMaybe I'm wrong but I suspect this might be partly due to the rise of Docker which makes attaching a debugger/profiler harder but also partly due to the existence of products like NewRelic which are like a hands-off version of a debugger and profiler. I haven't used a debugger much at work for years because it's all Docker (I know it's possible but lots of hoops to jump through, plus my current job has everything in AWS i.e. no local dev).
- inglor_cz 6mo agoOn the other hand, I had to debug a PHP app in Docker using XDebug and it was mostly painless. Or, to be more precise, no more painful than debugging it on local Wamp/Xampp.
- jamesfinlayson 6mo agoOh I know it's doable - I remember a two people that I used to work with individually getting it working. Most people didn't seem to want to bother though.
- materielle 6mo agoIt’s because in most enterprise contexts: 1) Most bugs are integration bugs. Whereby multiple systems are glued together but there’s something about the API contract that the various developers in each system don’t understand. 2) Most performance issues are architectural. Unnecessary round trips, doing work synchronously, fetching too much data. Debuggers and profilers don’t really help with those problems. I personally know how to use those tools and I do for personal projects. It just doesn’t come up in my enterprise job.
- ludston 6mo agoIf you don't have personal examples of using a profiler to diagnose an issue like "too many round trips" and identify where those round trips are coming from, then you've never inherited a complex performance problem before.
- rustystump 6mo agoThat is surprising. They have come up in every enterprise job i have had. Debuggers and profilers absolutely do help although for distributed systems they are called something else.
- gf000 6mo agoDoesn't really change the picture. If you don't know the basics of a car, then you absolutely shouldn't be driving in traffic either.
- munch-o-man 6mo agoyeah but that analogy is sort of false. A better analogy...but then it would make you look absurd...would be "if you don't know how to take apart and re-assemble the engine of a vehicle you shouldn't be allowed to drive it on the road". You get a driver's license if you can remember a few common sense facts and spend a bit of monitored time behind the wheel without doing anything absurdly illegal or injuring/killing somebody
- hrimfaxi 6mo agoYou don't use like Datadog or something at your enterprise job?