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Ice Thread Pool problem

alex_leshiialex_leshii Member Alex SamsonikOrganization: Donskoi State Technical UniversityProject: OCI middle f
Hi!
I've a problem in developing project with Ice 3.3.1 vs CodeGear 2009 SP4, wich works on Windows XP SP3.
My client-server applicaion works with session factory, timestamp and garbage thread (demo Sessions).
I add method GetResult (std:string& s, Ice::Current &) to the class SessionI, which uses client application to get data from the server:
class SessionI : public Demo::Session, public IceUtil::Mutex
{
public:

    SessionI(const std::string&);

    virtual Demo::HelloPrx createHello(const Ice::Current&);
    virtual void refresh(const Ice::Current&);
    virtual std::string getName(const Ice::Current&) const;
    virtual void destroy(const Ice::Current&);

    virtual void GetResult (std:string& s, Ice::Current &);

    IceUtil::Time timestamp() const;
....
};
Class OraProxy:

class OraProxy: puclic Ice::Object
{
	private:
		char *lname;
		....
	public:
		GetParseString(string& result_string);
};
typedef IceUtil::Handle<OraProxy> OraProxyPtr;

Then i described method GetResultin module SessionI.cpp:
void SessionI::GetResult(std::string& s,const Ice::Current&)
{
	OraProxyPtr op=new OraProxy();
	op->GetParseString(s);
	...
}

In method GetParseString of class OraProxy I try to allocate memory for field lname using code:
void OraProxy::executing_statement(std::string& result_string)
{
	numcols = 3;
	lname=(char*)calloc(1,numcols*MAXFETCH*((MAXLEN+1)*2));
	....
	free (lname);
	result_string = ...;
}

Now about problem. When clients connect to the server, which started whith parameter Ice.ThreadPool.Server.Size=1, all works well, but very slowly. But when i make Ice.ThreadPool.Server.Size more,then 1, my server works some time and then falls with Access violation error while executing method executing_statement.

P.S. I change type of field lname to vector and try to allocate memory with method resize(), but nothing changed.

Regards.

Comments

  • benoitbenoit Rennes, FranceAdministrators, ZeroC Staff Benoit FoucherOrganization: ZeroC, Inc.Project: Ice ZeroC Staff
    Hi and welcome to the forums!

    Did you manage to get a stack trace of the access violation to see if it helped narrowing down the issue? In any case, could you try with the latest Ice version and C++Builder 2010? We only support the latest Ice version for free here on the forums.

    Cheers,
    Benoit.
  • alex_leshiialex_leshii Member Alex SamsonikOrganization: Donskoi State Technical UniversityProject: OCI middle f
    Ice Thread Pool problem

    Hi, Benoit!
    I got stack trace, it says that after execution of function calloc raises exception (check attachment)
    Fuction calloc in my example allocates 750000 bytes. I change linker parameters heap size, maximum and stack size maximum to 0x100000 and tried to use Ice parameter Ice.ThreadPool.Server.StackSize=16777216, but no result.
    Also i wrote an algoritm, wich concatenates std::string string variables into result variable in cycle and got an acception in deallocation of memory.

    Thanks for help!
  • dwaynedwayne St. John's, NewfoundlandMember Dwayne BooneOrganization: ZeroC, Inc.Project: Internet Communications Engine
    Do you have any synchronization in place around the executing_statement method to prevent multiple threads from calling it concurrently? If not that could cause issues as you appear to be allocating/freeing a shared member variable in that function.
  • alex_leshiialex_leshii Member Alex SamsonikOrganization: Donskoi State Technical UniversityProject: OCI middle f
    Hi, Dwayne!
    If i use IceUtil::Mutex, everything is ok:) , but i want to execute this method in parallel mode.
    I use fields of the class OraProxy in the method executing_statement. When client connects to the server, I create a new object of the class OraSession, wich has local variables-fields for each object, not shared.
    If i made a mistake,correct me, please.

    Thank you for the help!
  • sgsoftsgsoft Member Samon SunOrganization: FreelanceProject: Remote RFID Reader
    I encountered a similar problem.
    I have a slice define like this:

    class server
    {
    void savedata(string data);
    }

    in savedata method,I use Oracle OCCI to save data.
    When I set the server thread pool size=1,all is ok,but when setting the size more then 1,the server process will make a hard CPU usage (99% above).

    env:
    VC 8.0
    ICE 3.3.1
    windows XP SP2;
  • benoitbenoit Rennes, FranceAdministrators, ZeroC Staff Benoit FoucherOrganization: ZeroC, Inc.Project: Ice ZeroC Staff
    Hi,

    This most likely indicates a thread safety issue with your code or with 3rd party code called from your servants. I recommend attaching to the process to see what the Ice server thread pool threads are doing, this might provide some hints on the cause of the hang.

    Cheers,
    Benoit.
  • sgsoftsgsoft Member Samon SunOrganization: FreelanceProject: Remote RFID Reader
    https://forums.oracle.com/forums/thread.jspa?threadID=422312

    Maybe it's oracle bug.

    I solve the problem use Application-Provided Serialization.

    You get more info from below link:
    Optimizing Performance of OCCI Applications
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