Visibility and happens before guarantee

[oblique bolt]

So I've watched video by Jakob Jenkov about Java synchronized keyword and blocks and methods. What it states is that:

Volatile happens before guarantee syays that any write to a field or variable that happens before write to a volatile variable are guaranteed to remain before writing to a volatole variable, so none of the instructions can be reordered to happen after the volatile variable.
Similarly any read of a variable that is read before the reads of other nonvolatile or volatile variables are guaranteed to happen before any of subsequent reads.

are these valid statements? Because i've to tried to verify this with LLM's and they are saying it's wrong.

[limpid merlin]

<@&987246964494204979> please have a look, thanks.

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TJ-Bot

So I've watched video by Jakob Jenkov about Java synchronized keyword and blocks and methods. What it states is that: Volatile happens before guarantee syays that any write to a field or variable that happens before write to a volatile variable are guaran

Yes, the volatile keyword in Java provides a happens-before guarantee, ensuring that any write to a volatile variable will be visible to all threads. This can help with ensuring synchronization and visibility of data across threads.

Useful links:

• Java volatile keyword
• Understanding the Java Memory Model
• Concurrency in Java: synchronized and volatile keywords

- AI generated response

[spare rivet]

yes

id suggest to read the wiki page for "happens-before"

its a topic that goes deep into cpu and vm internals and theory

https://en.wikipedia.org/wiki/Happened-before

[oblique bolt]

Doesn't seem huge topic

[spare rivet]

it is, if u dive deep enough

its quite complex to figure out the correct happens-before relationships between various lines of code