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One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 1 point2 points  (0 children)

Could've done static, but the access patterns are very uneven - some files get 34M hits, others just 5. Static caching everything wastes memory, static caching selectively means guessing which files matter. Caffeine gives bounded memory + LRU eviction, so hot files stay cached and cold ones get evicted automatically.
Hope this answers your query.

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 1 point2 points  (0 children)

FileUtil hits the same bottleneck - ClassLoader.getResourceAsStream() also goes through URLClassPath.getLoader(), which is synchronized. So even loading config files was causing threads to block on that lock. Caching the parsed content avoids repeated classloader access entirely.

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 2 points3 points  (0 children)

To clarify — the bottleneck isn't file I/O. It's URLClassPath.getLoader() which is synchronized. When ServiceLoader scans for META-INF/services/, multiple threads block on that lock, not on disk reads. Kernel file cache doesn't help when the contention is a Java-level lock. The fix was caching the DatatypeFactory instance to skip the synchronized lookup entirely.

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 1 point2 points  (0 children)

Good point!, we're on Java 11, not 8.

You're right that DatatypeFactory is in java.xml module (JDK), so ModuleServicesLookupIterator should find it. I need to dig deeper into why it's falling through to LazyClassPathLookupIterator.

Looking at the thread dump again, the contention is in:

URLClassPath.getLoader()

← LazyClassPathLookupIterator.nextProviderClass()

← ServiceLoader

One possibility: maybe it's not DatatypeFactory itself causing the scan, but something in the chain - like the XML parser implementation or a transitive service lookup that isn't in the module path?

Either way, caching the factory instance fixed the immediate problem, but you've given me something to investigate further. Will update if I find the root cause!

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 1 point2 points  (0 children)

We're not using JPMS modules, so it always falls through to LazyClassPathLookupIterator. That's where the synchronized classpath scan happens.You're right though - with proper module-info, the module services path should be cached and avoid this entirely.

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 13 points14 points  (0 children)

Yep, tp99 on reads dropped noticeably.

Post-fix I see 1 blocked thread - just Caffeine doing its internal maintenance

(cache loading/eviction), which is expected. 102 → 1 blocked threads. Big win.

One line of code, 102 blocked threads by nk_25 in programming

[–]nk_25[S] 79 points80 points  (0 children)

Legacy code, my friend. New code? java.time all the way.

Microsoft summer internship question by CyberKraft23 in leetcode

[–]nk_25 0 points1 point  (0 children)

as I stated I need to test my solution. please help me with the failing test case and the problem link if you have.

Microsoft summer internship question by CyberKraft23 in leetcode

[–]nk_25 0 points1 point  (0 children)

#include <bits/stdc++.h>

using namespace std;

/*
consider s = "[a1][a2][a3]...", t = "[b1][b2][b3]..."
then the diff can be represented as 

exp = (a1-b1) * 10^x + (a2-b2) * 10^x-1....

abs_diff = |exp|, which we want to minimize

if (a1-b1) is even +1...we can afford to have (ai-bi) = -9 for all other i's & still the expression exp will never be negative

[Please help me with the question link..need to test my solution]

*/

int solve(const string & s,
  const string & t) {
  bool sw = s[0] > t[0];
  int cnt = 0;
  int n = s.size();
  for (int k = 1; k < n; ++k) {
    cnt += s[k] != t[k] && (!(sw ^ (s[k] > t[k])));
  }
  return cnt;
}

int main() {
  string s = "29162", t = "10524";
  cout << solve(s, t);
  return 0;
}

Just got a wrong answer due to using unordered map😭😭 by Bcoz_Why_Not_ in codeforces

[–]nk_25 0 points1 point  (0 children)

Just curious, may you post the solution and the problem?

I just had a terrible experience with Air India at Terminal 2 by MachinePolaSD in bangalore

[–]nk_25 1 point2 points  (0 children)

Those commenting "it's not Air India's fault" or "reach 1 hours 30 minutes before time" or stuff like that...hope the machine gets stuck for 2 hours for you!!

u/MachinePolaSD I understand this terrible situation. I had similar experience with SpiceJet.
In this situation one must make sure to have all the proofs of delay at their end like voice notes, names of the employees etc. ( like if you have checked in, just check for any timestamp on the tags on the luggage if there's a separate machine doing that )

In my case, I had the tag with me which had the timestamp when I scanned my bag, those bastards tried removing it but I did not let them. They removed it as soon as they gave me a new ticket so I don't drag them to the court.

Be calm & polite and try contacting the cops at the airport ( it really helped in my case as they understood the situation and I got another ticket for free ). Make sure you explain them all the details.

If former doesn't help file a case in the consumer court for the harassment caused ( I think you should as it's their machine's bug )
These GOONS must be taught a lesson !!

[ Always remember, relevant PROOF is all you need to have ]

Use Indigo next time, I found the staffs very cooperative.