Latest news

NEW: FEBRUARY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "A puzzler related to a performance anti-pattern - getting a null pointer exception seemingly without a null"
• All the latest Java performance tips extracted in concise form
  • "Before Java 7u6 String.intern() was slow and not particularly efficient, nor was it tunable (and the internal String map was held in perm space). You were recommended to use your own WeakHashMap to create your own version of intern'ed strings. After Java 7u6 String.intern() is efficient, the map is now in the heap, and you can tune it's bucket size with -XX:StringTableSize= (default 1009 in Java 7, 60013 in Java 8)."

JANUARY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Locking is considered a pessimistic approach - you're assuming the worst case, that something else will try and change your value while you do, and so you lock them out so that you can guarantee you don't waste your operation. Compare-and-swap is an optimistic approach - you assume that mostly nothing else is going to change the value when you are, so it's best to just give it a go, and deal with (hopefully) the odd failure with a retry"
• All the latest Java performance tips extracted in concise form
  • "Multidimensional arrays (in Java) are arrays of arrays, so not necessarily close in physical memory. You can convert a multidimensional array to a linear array, e.g. using a calculated index like array[ROWS * col + row]. Make sure the inner loop is iterating over sequential elements, if you get this the wrong way round you'll just get cache misses all the time (i.e. NOT array[COLS * row + col], but array[ROWS * col + row] where the inner loop is for (int row=0; row < ROWS; row++)"

DECEMBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "quote of the year : when web companies grow up they turn into Java shops"
• All the latest Java performance tips extracted in concise form
  • "Thread pools have various strategies to deal with incoming work when all threads are busy, e.g.: rejecting the excess work; waiting; executing the job in the thread adding the work. In the last case, this could potentially cause the work pipeline to stall behind one work item, even if the pool becomes free to accept more work, so should be considered carefully. The symptom for this situation would be for the 'adding' thread to be busy while many of the pool threads become idle."

NOVEMBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Oracle are targeting providing deterministic low latency pauses in G1 - aiming for consistent deterministic pauses in the 10ms range"
• All the latest Java performance tips extracted in concise form
  • "Software-based contention management can improve the performance of hardware based compare-and-swap operations. By using contention management and backoff techniques, you can improve throughput by an order of magnitude at high contention, with only a small overhead at low contention"
• All Java performance books listed at fasterj.com

Previous newsletters

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How to use this site

This site has four main information resources:

• The uncategorized tips page lists many other web pages with Java performance tuning related information. Each web page has its performance tuning tips extracted and listed immediately after the URL is listed. These tips are being categorized, and the tips page links to those categories currently available. If the performance area you are interested in is not yet categorized, send us an email from this page telling us the categorization you'd like to see. In any of the tips pages, use your browser's "find" or "search" option to identify particular tips you are interested in on the page, and follow up by reading the referenced web page if necessary or desired.
• The resources page lists Java performance tuning resources including books, tools, reports, other performance tuning sites of interest, and Java performance tuning discussion groups.
• The news pages are monthly newsletters listing any new Java performance tuning related information, together with Kirk Pepperdine's discussion group roundup and Javva The Hutt.
• The tool reports pages are detailed introductory reports on various Java performance related tools, for both free and commercial tools.

This site has been designed to download almost as fast as possible. (Some stylistic markup and required server-side processing has been used in preference to absolute speed contraints.) The web tree contains very few graphics and almost no complex typesetting markup except for very simple tables, and the main pages can be accessed directly from the menu.

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