Hello!
I'm @captainsafia!
safia.rocks
content warning
this is a technical talk with no code.
@captainsafia
difficulty warning
this is a beginner-friendly talk!
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bit.ly/jmp-memlng-live
Follow along! 🎉
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turing machine
Von Neumann architecture
A machine that thinks is remarkable.
A MACHINE THAT REMEMBERS WHAT IT THINKS IS REVOLUTIONARY.
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""But my laptop has 16 gbs of memory.
Why should i care about memory performance?""
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truly timeless.
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Language agnostic.
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User expectations and demands grow faster than memory availability.
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Not all your users are using the latest tech.
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You don't want to be that app.
YOU KNOW THAT APP.
Let's go to class.
Premature freeing
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memory leak
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But we (kind of) don't have to worry about that.
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garbage collection
Sounds Great?
kind of.
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CPU Overhead
PAUSE TIMES
memory overhead
V8
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The Memory Heap
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Locality and fragmentation
how do you allocate memory?
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FIRST FIT
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BEST FIT
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WORST FIT
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That's the language agnostic stuff.
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V8 allocates objects in memory into contiguous chunks, or spaces.
-
New space
-
Old pointer space
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Old data space
-
Large object space
-
Code space
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So, we've allocated objects in memory.
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The Memory Heap
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But, how does V8 collect garbage memory?
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Run a short garbage collection cycle.
Halt the program.
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Scavenging
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from space
TO Space
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from space
TO Space
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from space
TO Space
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from space
TO Space
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from space
TO Space
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from space
TO Space
Mark and Sweep
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Marked as 0
Marked as 1
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Marked as 0
Marked as 1
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Marked as 0
Marked as 1
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Marked as 0
Marked as 1
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Marked as 0
Marked as 1
@captainsafia
Marked as 0
Marked as 1
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Marked as 0
Marked as 1
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intelligent Memory Allocation
+
nicely designed garbage collectors
=
less painful programming
How much memory is my application using?
How often do GC cycles occur in my application?
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The right tools for a messy job.
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Let's try it.
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-
memwatch
-
heapdump
-
v8-profiler
-
performance monitoring tools
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Enough with the v8, Already!
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chakra
uses mark and sweep
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chakra
runs the gc on a concurrent thread
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chakra
allocates scalars into a separate space
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chakra
(sometimes) runs the garbage collector on tab switch
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Spidermonkey
uses mark and sweep
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Spidermonkey
utilizes incremental marking
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Spidermonkey
has a compacting gc
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so we've got this knowledge.
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WHen should WE USE IT?
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""I had your To-do list app open in my browser and it makes it crash after a while!""
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""your app has jank and jitters""
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""your app just sucks""
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you can do it.
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memory management is hard.
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garbage collectors get better every day.
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v8 makes it easy and obfuscates the details from us.
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But eat your vegatables and appreciate your garbage collector. ❤️
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