The Dynamo Administration Interface pages for ClientLockManager and ServerLockManager components display the state of the internal tables for each lock entry. To view this information, click Display Lock Table under Service Info.
ClientLockManager lock table
The ClientLockManager lock table contains these columns:
Column heading | Value |
---|---|
Key | A string that identifies the locked item with this format:
|
Read owned | Set to true or false, indicates whether this client lock manager has a read lock on this item. Multiple client lock managers can simultaneously have the same read lock. One read lock on an item prevents other processes from obtaining a write lock. |
Write owned | Set to true or false, indicates whether this client lock manager has a write lock on the item. |
Read requested | Set to true or false, indicates whether a request is pending from another client to obtain a read/write lock. The ServerLockManager forwards client requests to all ClientLockManagers that own locks on the desired item. This field is set to true only when the Read owned or Write owned field is set to true and the lock request conflicts with active lock owners—for example, a write lock is requested for an item by another client when this client has a thread with active read ownership on that item. |
Globally owned | Set to true if an active read or write lock exists that was acquired from the ServerLockManager. If the ServerLockManager is unavailable, a client can distribute locks but sets this field to false, indicating that the lock is valid only for this client. |
Write owner | The thread that owns this lock in this client. |
Read owners | One or more threads that own this lock in this client. |
Read waiters | The threads that are waiting for this lock. |
ServerLockManager Lock Table
The ServerLockManager lock table contains these columns:
Column heading | Value |
---|---|
Key | A string that identifies the locked item with this format:
|
Write owner | The client that owns this lock. |
Read owners | One or more clients that own this lock. |
Read waiters | The client IDs that are waiting for this lock. |