Resolving JCO_ERROR_CONCURRENT_CALL in JCo

Resolving JCO_ERROR_CONCURRENT_CALL in JCo

How do I resolve the error "JCO_ERROR_CONCURRENT_CALL" when running SAP JCo in a Web application?

Here is the exception report:
com.sap.mw.jco.JCO$Exception: (132) JCO_ERROR_CONCURRENT_CALL: Concurrent call. Connection currently used in another thread.
at com.sap.mw.jco.JCO$Client.execute(Unknown Source)
at com.sap.mw.jco.JCO$Client.execute(Unknown Source)
at com.sap.mw.jco.JCO$Repository.execute(Unknown Source)
at com.sap.mw.jco.JCO$Repository.queryFunctionInterface(Unknown Source)
at com.sap.mw.jco.JCO$Repository.queryFunctionInterface(Unknown Source)
at com.sap.mw.jco.JCO$Repository.getFunctionInterface(Unknown Source)
at com.sap.mw.jco.JCO$BasicRepository.getFunctionTemplate(Unknown Source)

    Requires Free Membership to View

    When you register, you will start receiving targeted emails from my award-winning team of editorial writers. Our goal is to keep you informed on the hottest topics and biggest challenges faced by SAP professionals today.

    Hannah Smalltree, Editorial Director

    By submitting your registration information to SearchSAP.com you agree to receive email communications from TechTarget and TechTarget partners. We encourage you to read our Privacy Policy which contains important disclosures about how we collect and use your registration and other information. If you reside outside of the United States, by submitting this registration information you consent to having your personal data transferred to and processed in the United States. Your use of SearchSAP.com is governed by our Terms of Use. You may contact us at webmaster@TechTarget.com.

From the looks of the exception, you have inadvertently created a singleton instance of the JCo connection somewhere and are trying to use the same connection at the same time. The best way to resolve this is to use JCo's built-in connection pooling. A JCo connection pool can be setup when the server launches and provide connections to any number of clients connected to the server (depending on the number of connections you make available in the pool). Do a search for "jco connection pool" on SearchSAP.com for tips on how to implement a connection pool in SAP JCo.

This was first published in July 2006