Enhancing i/o performance using in-memory reservation state caching at block storage services

A computer-implemented method, comprising:

• determining, at a first worker thread of a plurality of worker threads of a first storage server of a storage service, that a command to modify a reservation record has been received, wherein the reservation record comprises access permissions to an object which is stored at least in part at the first storage server;
• acquiring, by the first worker thread in exclusive mode, a first lock of a plurality of locks associated with the reservation record, wherein a first version of the reservation record is stored in a cache maintained in main memory of the first storage server, wherein the cache is populated at least in part by copying the first version from a metadata store;
• acquiring, by the first worker thread in shared mode while holding the first lock in exclusive mode, a second lock of the plurality of locks;
• releasing the second lock by the first worker thread after generating, in accordance with the command to modify the reservation record, a second version of the reservation record, wherein the second lock is released without storing the second version in the cache;
• verifying, by the first worker thread, that respective entries comprising the second version of the reservation record have been stored in a plurality of replicas of an operations journal;
• acquiring, by the first worker thread, the second lock in exclusive mode after said verifying;
• storing, by the first worker thread while holding the second lock in exclusive mode, the second version of the reservation record in the cache;
• releasing, by the first worker thread, the second lock and the first lock;
• and
• causing, by the first worker thread, an indication that the command to modify the reservation record has succeeded to be transmitted, without verifying that the second version of the reservation record has been stored in the metadata store.

A non-transitory computer-accessible storage medium storing program instructions that when executed on a processor:

• determine, at a first worker thread of a plurality of worker threads of a first storage server of a storage service, that a request to modify a reservation record has been received, wherein the reservation record comprises access permissions to an object which is stored at least in part at the first storage server;
• acquire, by the first worker thread in exclusive mode, a first lock of a plurality of locks associated with the reservation record, wherein a first version of the reservation record is stored in a cache maintained in main memory of the first storage server, wherein the cache is populated at least in part by copying the first version from a metadata store;
• acquire, by the first worker thread in shared mode while holding the first lock in exclusive mode, a second lock of the plurality of locks;
• release the second lock by the first worker thread after generating, in accordance with the request to modify the reservation record, a second version of the reservation record, wherein the second lock is released without storing the second version in the cache;
• verify, by the first worker thread, that respective entries comprising the second version of the reservation record have been stored in a plurality of replicas of an operations journal;
• acquire, by the first worker thread, the second lock in exclusive mode after verification that the respective entries comprising the second version have been stored;
• store, by the first worker thread while holding the second lock in exclusive mode, the second version of the reservation record in the cache;
• release, by the first worker thread, the second lock and the first lock;
• and
• cause, by the first worker thread, an indication that the request to update the reservation record has succeeded to be transmitted, without verifying that the second version of the reservation record has been stored in the metadata store.