Could not reserve enough space for object heap

Bonjour à tous.

J'ai constaté que mon serveur tomcat plante souvent lorsque je fais des tests de charge via j-meter.

Je suis sur un serveur 4 coeur dont la mémoire est de 6Go et où le PAE est activé.

J'ai donc tout simplement testé par dichotomie la valeur maximum que je peux allouer à la JVM, et ce maximum est de 2.7Go.

Pourquoi ne puis-je pas allouer plus de mémoire à ma JVM ?

Citation:

java -Xmx2700m -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.

FREE

Citation:

total used free shared buffers cached
Mem: 6096924 861924 5235000 0 76800 580968
-/+ buffers/cache: 204156 5892768
Swap: 2040244 0 2040244

cat /proc/meminfo

Citation:

MemTotal: 6228500 kB
MemFree: 5175508 kB
Buffers: 46176 kB
Cached: 849264 kB
SwapCached: 0 kB
Active: 337696 kB
Inactive: 658632 kB
HighTotal: 5372252 kB
HighFree: 4417408 kB
LowTotal: 856248 kB
LowFree: 758100 kB
SwapTotal: 2040244 kB
SwapFree: 2040244 kB
Dirty: 5340 kB
Writeback: 0 kB
Mapped: 118356 kB
Slab: 41172 kB
CommitLimit: 5154492 kB
Committed_AS: 263712 kB
PageTables: 1908 kB
VmallocTotal: 106488 kB
VmallocUsed: 2608 kB
VmallocChunk: 103436 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 2048 kB

vmstat

Citation:

vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 0 0 5143060 48320 880140 0 0 30 100 562 146 2 1 96 1

Je vous remercie d'avance pour vos solutions :aie:

Personne n'a rencontré ce problème?

Pourquoi tu as besoin d'autant de mémoire ?

bonjour fr1man,

J'en ai besoin pour effectuer des benchs sur des webservices, pour identifier le nombre maximum de clients qui peuvent se connecter. Et tomcat est très gourmand en ressources.

As-tu une solution à mon problème ?

A priori, cela dépend de l'OS et de la JVM, sachant que sur une JVM 64 bits, il n'y aurait pas de limites.

Effectivement, après une recherche un peu plus approfondi, voilà ce que j'ai trouvé sur le site de sun :

Citation:

The VM prints "OutOfMemoryError" and exits. Increasing max heap size doesn't help. What's going on?

The Java HotSpot VM cannot expand its heap size if memory is completely allocated and no swap space is available. This can occur, for example, when several applications are running simultaneously. When this happens, the VM will exit after printing a message similar to the following.

Exception java.lang.OutOfMemoryError: requested <size> bytes

If you see this symptom, consider increasing the available swap space by allocating more of your disk for virtual memory and/or by limiting the number of applications you run simultaneously. You may also be able to avoid this problem by setting the command-line flags -Xmx and -Xms to the same value to prevent the VM from trying to expand the heap. Note that simply increasing the value of -Xmx will not help when no swap space is available.
For more information, see the evaluation section of bug 4697804.

Why can't I get a larger heap with the 32-bit JVM?

The maximum theoretical heap limit for the 32-bit JVM is 4G. Due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead, in practice the limit can be much lower. On most modern 32-bit Windows systems the maximum heap size will range from 1.4G to 1.6G. On 32-bit Solaris kernels the address space is limited to 2G. On 64-bit operating systems running the 32-bit VM, the max heap size can be higher, approaching 4G on many Solaris systems.

As of Java SE 6, the Windows /3GB boot.ini feature is not supported.

If your application requires a very large heap you should use a 64-bit VM on a version of the operating system that supports 64-bit applications. See Java SE Supported System Configurations for details.

Donc théoriquement c'est possible que je puisse augmenter mon heap space. En jouant sur l'espace swap, le kernel ...

Sinon comme tu le dis, reste la solution de passer en OS 64bits...Et ce n'est pas prévu actuellement.

En tout cas merci, je suis fixé sur le pourquoi de la chose...

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