FAQ

Will Oracle continue to invest in JRockit technology?
Absolutely! JRockit is a strategic product for Oracle and its customers. Oracle will continue to invest in it significantly. Oracle will continue to pay attention to legacy-BEA and Oracle customers needs and customers should expect a strong roadmap for the JRockit JVM and all JRockit products.

Going forward, is JRockit going to be free or a for-charge product?
Consistent with Oracle policies, JRockit Mission Control and JRockit Real Time, which include the JRockit JVM and access to significant value-adds such as operations diagnostics and real-time features, are available for development and evaluation for free. It is also bundled with many other commercial products from Oracle.

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Hueniverse: Scaling a Microblogging Service - Part I

The social web is creating demand for new scaling tools and
technologies. Current databases and caching solutions are simply unable
to handle a complex network of multiple relationship between objects.
While databases are still a good solution for persistent storage of
social data, each retrieval requires heavy calculation.

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int64.org » Scalability isn’t everything

… application needed a queue of small objects, and on a modern quad–core CPU the cache misses were hurting performance so much that although a lock–free queue did have near 100% scalability, the overall operation was completing 165% faster with a locked queue with zero scalability.

The next best thing is to combines the best of both worlds: design a queue with low overhead and medium scalability. Using a reader–writer lock with a combination of lock–free operations, I came up with a queue that only needs to do a full lock once every 32 or 64 operations. The result? Scalability 5% lower than a lock–free queue, with overall performance 210% better.

OK, I’ll admit it: I cheated, somewhat. Lock–free algorithms are good for more than just scalability. They also offer immunity to nasty effects like deadlock, livelock, and priority inversion. In my case I wasn’t in a situation to worry about these, but you might be. The lesson here is to know your situation and decide carefully, and don’t trust what others tell you: always try things yourself and profile.

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Scaling Audiogalaxy to 80 million daily page views | Spiteful.com

For our most heavily accessed data set, we had an extremely good read/write ratio, so we were able to fan out to about 20 slaves from a single master. This particular database had several hundred million rows, which challenged the limits of our hardware (periodically, we had to clean out stale data when it got too large), so one trick we used was index-segmentation. Different sets of slaves had different indexes, and our database access layer could pick a different cluster based on the necessary index. Specifically, the tables in this database generally had an ID and a string, but the index on the string was only necessary for some queries. So, on some slaves we simply didn’t have the string index. This allowed those machines to keep the entire ID index in memory, which was a huge performance boost.

We used sharding to scale our databases in other areas.

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FreeBSD 7.0-RELEASE Release Notes

A new malloc(3) implementation has been introduced. This implementation, sometimes referred to as “jemalloc”, was designed to improve the performance of multi-threaded programs, particularly on SMP systems, while preserving the performance of single-threaded programs. Due to the use of different algorithms and data structures, jemalloc may expose some previously-unknown bugs in userland code, although most of the FreeBSD base system and common ports have been tested and/or fixed. Note that jemalloc uses mmap(2) to obtain memory and only uses sbrk(2) under limited circumstances (and then only for 32-bit architectures). As a result, the datasize resource limit has little practical effect for typical applications. The vmemoryuse resource limit, however, can be used to bound the total virtual memory used by a process, as described in limits(1).

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