[vbox-dev] API method execution sometimes extremely slow

Nikolay Igotti igotti at gmail.com
Tue Dec 24 21:25:42 GMT 2013

Hi Thorsten,

Couldn't it be GC pauses in your JVM? Try appropriate JVM logging or 
JConsole to see if
there's correlation between slow calls and GC.


11.12.2013 16:14, Klaus Espenlaub пишет:
> Hi Thorsten,
> On 10.12.2013 14:44, email at thorstenschaefer.de wrote:
>> Hi,
>> I am using VirtualBox 4.3.4 on MacOS Maverick. The VM is a Windows 7
>> 64bit guest running on a Macbook Pro (8 cores, 16GB RAM). The issue I
>> have is as described at
>> https://forums.virtualbox.org/viewtopic.php?f=34&t=57685:
>> When using the API methods over Java using XPCOM, some method calls
>> randomly take a huge amount of time. For instance, things that are
>> typically done within 1-5ms sometimes take up to 2000ms! Even when these
>> delays happen, the CPU usage is never even near 100% and their is
>> sufficient free memory on the host available. I wonder if someone can
>> give me insights into what might cause these kind of delays and if its
>> maybe possible to communicate more quickly. For instance, if its caused
>> by interprocess scheduling, is it possible to “open a stream” and then
>> just send the commands to it? Fwiw, if I perform the same stuff (e.g.
>> Key clicks) manually within the VM, there are never delays like this
>> observable.
> Never seen such problems, and as the Java/XPCOM combo in the end
> interfaces to the C++ API which is used by every VirtualBox component
> (the manager GUI and the VM processes) I doubt that there's a generic issue.
> When does the big delay happen? Is it really for individual API calls,
> or do you count in the setup time (getting the VirtualBox reference,
> setting up a session)?
> We don't write much Java code, and don't actively use this way of
> talking to the API, but we're quite sure that more than only a few
> people go this way.
> Klaus
>> Cheers,
>> Thorsten
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