The road to the architect fourth day Tomcat performance tuning-let the kitten Gallop

One, summing up the study of the day before

From the "Third Day" performance Test section, we learned several important metrics for the deterministic test:

• throughput

Üresponsetime

Ücpuload

Ümemoryusage

We have also done a certain optimization on the third day of study in Apache, to optimize the above 4 key readings, then our Apache tuning, our tomcat also make some corresponding adjustments, when the completion of this course, when your "kitten" will really "fly" up to the, So please read, this article on the one hand to the one who has written "Tomcat how to withstand 1000 users," the respect, on the one hand, is an extension of the original text, because in the original knowledge used in the relevant two major projects to solve after the:

1 to bear the number of concurrent users

2 achieved good performance and improvement (System average performance up to 20 times times, extreme one transaction up to 80 times times).

Another value is that we used the project "Kitten" is run under the 32-bit machine, that is, our JVM is the largest 2GB memory limit, have been running to "fly" ... If you run this "kitten" in a 64-bit machine ... We can imagine, what will be the effect of it? Please set the details below!

Second, everything based on the JVM (memory) optimization

2.1 32-bit operating system vs JVM in 64-bit operating system

Our average developer, basically, is a 32-bit Windows system, which leads to a serious problem: 32-bit Windows system for memory limits, let's look at a comparison table:

Operating system	Number of operating system digits	Memory Limits	Solutions
Winxp	32	4GB	Super Bunny
Win7	32	4GB	You can set/PAE by setting the
Win2003	32	Can break through 4GB up to 16GB	You will need to install Win2003 Advanced Server and make SP2 patches.
Win7	64	Unlimited	How much memory can be plugged into the machine, how much the system memory can support
Win2003	64	Unlimited	How much memory can be plugged into the machine, how much the system memory can support
Linux	64	Unlimited	How much memory can be plugged into the machine, how much the system memory can support
Unix	64	Unlimited	How much memory can be plugged into the machine, how much the system memory can support

After solving the problem, we have a new problem, 32-bit system under the JVM on the memory limit: not to break through 2GB memory, even if you are under the Win2003 Advanced server your machine is equipped with 8GB-16GB memory, and your Java, can only use 2GB of memory.

In fact, I always want to recommend the use of Linux or Mac operating system, and to install 64, because we are not developed to play with the game, and Java originated from UNIX to Unix (Linux is only running on the PC on the UNIX and its own).

So a lot of developers are running on the Win32 bit system, even in the production environment will be the Win32 bit of the system, then your tomcat to optimize, you need to pay attention to some skills. in 64-bit operating systems, both system memory and the JVM are not limited by 2GB.