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Joined 3 years ago
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Cake day: September 10th, 2023

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  • I’m going to whoosh the joke for a moment.

    Avoid allocating memory in sig segv handlers. I worked at a company once that had written their own handlers that tried to print a stack trace. I was fortunate enough to find a machine in a test environment that segfaulted while allocating memory. The handler then caused a deadlock in a call to malloc (through new). I ended up rewriting the handler to fix two sources of memory allocation. First I preallocate enough space to do string manipulations in the handler. Second I made eager calls to a few libc functions used in the handler to avoid memory allocation from lazy binding from ld.so.





  • BlazeDaley@lemmy.worldtoScience Memes@mander.xyzRIP America
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    10 months ago

    I’m not disagreeing. The report isn’t clear. This is written by people asking Congress for a budget cut.

    NSF programs indirectly impact millions of people, reaching PreK-12 students and teachers, the general public, and researchers

    The actual impact to the pipeline may be far larger.


  • BlazeDaley@lemmy.worldtoScience Memes@mander.xyzRIP America
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    10 months ago

    Graduate students provide enormous value for their cost in funding. I’d like to better understand how k-12 students contribute here. Those students make up 88.7k of the reduction. How much do these students contribute and at what cost?

    I’m in no way against inspiring the next generation. My question is aimed at correctly interpreting this table. The NSF is a worthwhile expense, but let’s understand the data we have.








  • BlazeDaley@lemmy.worldtoScience Memes@mander.xyzPhysics
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    2 years ago

    We have a mathematical model, Navier-Stokes (NS), that seems to describe motion of fluids well. In practice NS and related approximation models with simpler numerical solutions can be used to derive useful results. In that sense we can simulate turbulence for some sets of conditions and get useful approximations out. In general it’s still an open problem if NS has, given an initial velocity field, a solution that is globally defined and smooth. Practically this means we don’t know one way or the other if NS has initial conditions under which the velocity or pressure fields of the solution tend to infinity in finite time. This is the unsolved Navier-Stokes problem.

    https://en.m.wikipedia.org/wiki/Navier–Stokes_existence_and_smoothness