Java Download Safe [BEST]

I know SimpleDateFormat and Calendar classes are not thread safe, which is why I configure one thread to always create new instances of them. But what about TimeZone? It is not clear to me whether I can do the following safely:

The only way you can get into trouble is by changing the id and caching your self the timezone, if you get it always from the TimeZone.getTimeZone() you are safe too, because that method is thread safe.

Java Download Safe

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You are not modifying your TimeZone, so your code should be thread safe regardless of whether the underlying implementation of TimeZone is thread safe (with the exception of static methods, like (getTimeZone/getDefault/setDefault).

A few years ago, there was a lot of advice to not use Java. It was buggy and easy for malware to exploit. Then people stopped talking about it. No software is absolutely safe, but given that I'm willing to take chances with Microsoft Windows, Adobe Reader, and well ... the Internet, is today's Java just as safe as they are?

"non-volatile writes [...] don't establish a happens-before relationship between the write and subsequent reads that see the written value. This means that a thread can see a new map published through the instance variable, but this new map hasn't been fully constructed yet. This is not intuitive, but it's a consequence of the memory model, and it happens in the real word. For an object to be safely published, it must be written to a volatile, or use a handful of other techniques.

No, this is not thread safe without volatile, even apart from the issues of seeing stale values. Even though there are no writes to the map itself, and reference assignment is atomic, the new Map has not been safely published.

For an object to be safely published, it must be communicated to other threads using some mechanism that either establishes a happens-before relationship between the object construction, the reference publication and the reference read, or it must use a handful of narrower methods which are guaranteed to be safe for publishing:

Your code is fine. You need volatile, otherwise your code would be 100% thread-safe (updating a reference is atomic), however the change might not be visible to all the threads. It means some threads will still see the old value of store.

If you want/need to run java apps you will need to install java. There are no safety issues greater than running any other app. Are you really asking about java or are you referring to javascript? Users often get these two different things confused.

I do agree that the language is not the problem. The problem is the implementation into a web browser. In the past we had the "applet" tag when writing HTML code that is now deprecated, but can still be embedded with the "object" tag. It still requires the JRE (Java Runtime Environment) that adds an extra layer that affects both Performance and Security. HTML 5 has eliminated the need to have any java plugin in a web browser and if I browse to a site the requires the Java plugin, I would be very suspicious.

I have the same question, and it's about java, not javascript. In order to install some mods for Minecraft, I have to install java. Since Apple parted with java in a previous OS I wasn't sure if it would be harmful to install java. Also wasn't sure what version of Java to install. I'm running 13.4, haven't upgraded to 14 just yet.

but back in the day java had a plugin for java applets that ran in a browser and that had tons of security issues sort of like flash, java for local apps is not a problem really apart from oracle not really managing it java very well so it can be a world of hurts to get working

The Java programming language is becoming popular daily due to its speed, efficiency, security, and readability. Java developers are also in demand as more businesses are using digital technology. So, is Java safe as compared to other programming languages? Java has robust security capabilities, and this is the main reason that many companies are using it.

Synchronization is the tool using which we can achieve thread-safety, JVM guarantees that synchronized code will be executed by only one thread at a time. java keyword synchronized is used to create synchronized code and internally it uses locks on Object or Class to make sure only one thread is executing the synchronized code.

Now we are going to describe the concept of safe publication. Safe publication differs from a regular publication on one crucial point. Safe publication makes all the values written before the publication visible to all readers that observed the published object. It is a great simplification over the JMM rules of engagement with regards to actions, orders and such.

Classic holder idiom does roughly the same, but piggy-backs on class initialization locks. It safely publishes the object by doing the initialization in the static initializer. Note this thing is lazy, since we do not initialize Holder until the first call to get():

Moving on. Java allows us to declare an object in a manner always safe for publication, that is, provides us with an opportunity for safe initialization. Safe initialization makes all values initialized in constructor visible to all readers that observed the object, regardless of whether the object was safely published or not. Java Memory Model guarantees this if all the fields in object are final and there is no leakage of the under-initialized object from constructor. This is an example of safe initialization:

A final field was written. Notice we do not care about what field was actually written, we unconditionally emit the barrier before exiting the (initializer) method. That means if you have at least one final field write, the final fields semantics extend to every other field written in constructor. That means this one can be a safe initialization given this simple VM implementation:

Notice how "fun" it would be for the actual software: you remove the "barrier" field in the course of some cleanup and/or refactoring, and an unrelated field starts to contain garbage after a unsafe publication.

A volatile field was written on PPC. This is a courtesy of PPC implementation, not required by spec, strictly speaking. But without it, some very trivial scenarios, like unsafe publication of user-initialized AtomicInteger could see under-initialized instance of it.

We can see that the failure happens when an unsafely constructed Singleton meets the unsafely publishing SingletonFactory.This is not an advice for programming dangerously. Rather, this is an example of "defense in depth", where failing in one place does not break correctness for the entire program.

Again, we see the failures when an unsafely initialized singleton meets an unsafely publishing singleton factory, like in x86 case. Notice that we did not used any compiler fuzzers at this point: this is the result of actual hardware reordering, not the compiler reordering.

The case of Unsafe DCL + Safe Singleton is interesting and stands out. There is a race in Unsafe DCL factory which is responsible for breakage: we observe null singleton. This is something that strikes people as odd, but it is legal in JMM. This is another example that final-s can save you from observing the under-initialized object, but can not save you from not seeing the object itself!

Notice how doing synchronized in Unsafe DCL store does not help, contrary to layman belief it somehow magically "flushes the caches" or whatnot. Without a paired lock when reading the protected state, you are not guaranteed to see the writes preceding the lock-protected write.

first_ cases when we request the Singleton instance off the freshly-baked SingletonFactory. This may help to estimate the upfront costs of seeding the factory, which would also include safe initialization cost, plus the "publishing" side of safe publication.

steady_ cases when SingletonFactory is already populated with Singleton instance, and we arguably go through the internal fast-paths. This case is reasonable to measure in multiple threads (under contention), to see how SingletonFactory performs under load. This will cover the "consuming" side of safe publication costs.

All other factories are performing more or less the same. This is true even for Unsafe DCL, which is functionally broken. This is evidence that correctly synchronized code does not always work slower than "tricky" incorrect code.

Unsafe DCL is even faster, because no volatile reads are happening at all. Remember, most tests involving Unsafe DCL are functionally broken. Those 3-6 ns difference between Unsafe DCL and Safe DCL seems to be a fair price for correctness.

Safe Publication and Safe Initialization idioms are great abstractions over Java Memory Model rules. Used carefully, these idioms can be used as building blocks for constructing larger concurrent programs without breaking correctness. The performance costs for these idioms are usually drowned in all other costs. In the singleton examples above, while the costs are measurable, the cost of allocation, or the cost of additional memory dereference may greatly offset the cost of the safe initialization/publication pattern itself.

Safe Initialization does not magically save you from all the races. If you are doing the racy reads of otherwise safely initialized objects, something can still go haywire. Racy reads themselves are almost pure evil, even on the platforms that are very forgiving, like x86. 2351a5e196