Aiding resolution of a transaction

A system comprising:

• one or more processors;
• and
• a computer readable storage medium coupled to the one or more processors, the computer readable storage medium storing program instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
• in response to a communications failure between a transaction coordinator and a first resource manager of a plurality of resource managers within a transactional processing system, connecting, by the transaction coordinator, to a second resource manager, the communications failure associated with an in-doubt state of a transaction;
• determining an association of the transaction with the first resource manager and an in-doubt state of the transaction, data associated with the transaction being in a first subset of a log of the first resource manager;
• based on the association and the in-doubt state of the transaction, obtaining a shared lock on a second subset of the log, the lock permitting one or more resource managers to access the log and preventing the first resource manager from accessing the second subset of the log;
• determining a difference in sizes of the first subset and the second subset after obtaining the shared lock;
• in response to determining the difference in sizes, releasing the shared lock;
• in response to releasing the shared lock, obtaining a subsequent lock on the second subset of the log, the subsequent lock being an exclusive lock obtained by a specified resource manager;
• in response to determining sizes of the first subset and the second subset are different, repeating obtaining one or more additional exclusive locks on a changed portion of the second subset of the log;
• in response to determining the sizes of the first subset and the second subset are the same, writing, by the specified resource manager, a resolution to the log of the first resource manager;
• and
• releasing the one or more additional exclusive locks responsive to writing the resolution of the log.

A non-transitory_computer readable storage medium storing program instructions that, when executed by one or more processors of a transactional processing system, cause the one or more processors to perform operations comprising:

• in response to a communications failure between a transaction coordinator and a first resource manager of a plurality of resource managers within a transactional processing system, connecting, by the transaction coordinator, to a second resource manager, the communications failure associated with an in-doubt state of a transaction;
• determining an association of the transaction with the first resource manager and an in-doubt state of the transaction, data associated with the transaction being in a first subset of a log of the first resource manager;
• based on the association and the in-doubt state of the transaction, obtaining a shared lock on a second subset of the log, the lock permitting one or more resource managers to access the log and preventing the first resource manager from accessing the second subset of the log;
• determining a difference in sizes of the first subset and the second subset after obtaining the shared lock;
• in response to determining the difference in sizes, releasing the lock;
• in response to releasing the shared lock, obtaining a subsequent lock on the second subset of the log, the subsequent lock being an exclusive lock obtained by a specified resource manager;
• in response to determining sizes of the first subset and the second subset are different, repeating obtaining one or more additional exclusive locks on a changed portion of the second subset of the log;
• in response to determining the sizes of the first subset and the second subset are the same, writing, by the specified resource manager, a resolution to the log of the first resource manager;
• and
• releasing the one or more additional exclusive locks responsive to writing the resolution of the log.