131–140 of 259 posts
First request latency also can really suck in Java before hotpathed code gets through the C2 compiler. You can warm up hotpaths by running that code during startup, but it's really annoying having to do that. Using C++, Go, or Rust gets you around that problem without having to jump through the hoops of code path warmup. I wish Java had a proper compiler.
"Java is slow" is a reputation it earned in the 90s/2000s because the JVM startup (at least on Windows) was extremely slow, like several seconds, with a Java-branded splash screen during that time. Even non-technical people made the association.
Understanding algorithmic complexity (in particular, avoiding rework in loops), is useful in any language, and is sage advice. In practice though, for most enterprise web services, a lot of real world performance comes down to how efficiently you are calling external services (including the database). Just converting a loop of queries into bulk ones can help loads (and then tweaking the query to make good use of inde…
When you're using a programming language that naturally steers you to write slow code you can't only blame the programmer. I was listening to someone say they write fast code in Java by avoiding allocations with a PoolAllocator that would "cache" small objects with poolAllocator.alloc(), poolAllocator.release(). So just manual memory management with extra steps. At that point why not use a better language for the tas…
A second bug is that Character.isDigit() returns true for non-ASCII Unicode digits as well, while Integer.parseInt() only supports ASCII digits.
Another bug is that the code will fail on the input string "-".
Lastly, using value.isBlank() is a pessimization over value.isEmpty() (or just checking value.length(), which is read anyway in the next line), given that the loop would break on the first blank character. It makes the function not be constant-time, along with the first point above that the length of the digit sequence isn’t being limited.
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public int parseOrDefault(String value, int defaultValue) {
if (value == null || value.isBlank()) return defaultValue;
for (int i = 0; i Understanding algorithmic complexity (in particular, avoiding rework in loops), is useful in any language, and is sage advice. In practice though, for most enterprise web services, a lot of real world performance comes down to how efficiently you are calling external services (including the database). Just converting a loop of queries into bulk ones can help loads (and then tweaking the query to make good use of inde…
I've always found ORMs to be performance killers. It always worked out better to write the SQL directly. The idea that you should have a one-to-one correspondence between your data objects and your database objects is disastrous unless your data storage is trivial.
When using JDBC I found myself quickly in implementing a poor mans ORM.
Avoiding Java's string footguns is an interesting problem in programming languages design. The String.format() problem is most immediately a bad compiler and bad implementation, IMO. It's not difficult to special-case literal strings as the first argument, do parsing at compile time, and pass in a structured representation. The method could also do runtime caching. Even a very small LRU cache would fix a lot of commo…
Yeah, Java is pretty fast despite the fact that it still has these kinds of obviously suboptimal things going on. I love how Zig, D and Rust do exactly what you say: parse the format string at compile time, making it super efficient at runtime (no parsing, no regex, just the optimal code to get the string you need). I say this but I write most of my code in Java/Kotlin :D . I just wish I could write more low-level la…
The code: public int parseOrDefault(String value, int defaultValue) { if (value == null || value.isBlank()) return defaultValue; for (int i = 0; i Is probably worse than Integer.parseInt alone, since it can still throw NumberFormatExceptions for values that overflow (which is no longer handled!). Would maybe fix that. Unfortunately this is a major flaw in the Java standard library; parsing numbers shouldn't throw exp…
Understanding algorithmic complexity (in particular, avoiding rework in loops), is useful in any language, and is sage advice. In practice though, for most enterprise web services, a lot of real world performance comes down to how efficiently you are calling external services (including the database). Just converting a loop of queries into bulk ones can help loads (and then tweaking the query to make good use of inde…
> ditch ORMs ... make good use of SQL I think Java (or other JVM languages) are then best positioned, because of jooq. Still the best SQL generation library I've used.
When you're using a programming language that naturally steers you to write slow code you can't only blame the programmer. I was listening to someone say they write fast code in Java by avoiding allocations with a PoolAllocator that would "cache" small objects with poolAllocator.alloc(), poolAllocator.release(). So just manual memory management with extra steps. At that point why not use a better language for the tas…
TBH, I do not see how Java as a language steers anyone to use one those shotguns. E.g. the knowledge about algorithmic complexity is foundational, the StringBuilder is junior-level basic knowledge.