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Description
Description
I encountered an infinite loop while using the SCAN command with pattern matching in Redis via AWS ElastiCache.
The issue arises when querying Redis for keys using a pattern (users:*)
. The loop keeps executing even when no more keys match the given pattern.
Below code to reproduce the issue
async function getActiveUsers(redisClient) {
const activeUserQueryPattern = `users:*`;
let cursor = 0;
let activeUsers = [];
console.log("Querying Redis for Active Users pattern :: ", activeUserQueryPattern);
do {
const userQueryData = await redisClient.scan(cursor, {
MATCH: activeUserQueryPattern,
COUNT: 100,
});
console.log("User Query Data :: ", userQueryData);
activeUsers = activeUsers.concat(userQueryData.keys);
cursor = userQueryData.cursor;
} while (cursor !== 0);
console.log('Active Users :: ', activeUsers);
return activeUsers;
}
I have fixed with checking keys length for now, but actually the cursor will return with zero, if there is not keys.
async function getActiveUsers(redisClient) {
const activeUserQueryPattern = `users:*`;
let keyLen = 1;
let activeUsers = [];
console.log("Querying Redis for Active Users pattern :: ", activeUserQueryPattern);
do {
const userQueryData = await redisClient.scan(cursor, {
MATCH: activeUserQueryPattern,
COUNT: 100,
});
console.log("User Query Data :: ", userQueryData);
activeUsers = activeUsers.concat(userQueryData.keys);
keyLen = userQueryData.keys.length;
} while (keyLen !== 0);
console.log('Active Users :: ', activeUsers);
return activeUsers;
}
Node.js Version
node v18.18.0
Redis Server Version
ElasticCache (Redis Version 7.1)
Node Redis Version
4.7.0
Platform
Windows
Logs
2024-12-07T15:33:22.237+05:30
2024-12-07T10:03:22.237Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.247+05:30
2024-12-07T10:03:22.247Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.249+05:30
2024-12-07T10:03:22.249Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.252+05:30
2024-12-07T10:03:22.252Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.255+05:30
2024-12-07T10:03:22.255Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.267+05:30
2024-12-07T10:03:22.267Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.270+05:30
2024-12-07T10:03:22.270Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.272+05:30
2024-12-07T10:03:22.272Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.275+05:30
2024-12-07T10:03:22.275Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.290+05:30
2024-12-07T10:03:22.290Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.292+05:30
2024-12-07T10:03:22.292Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.294+05:30
2024-12-07T10:03:22.294Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.307+05:30
2024-12-07T10:03:22.307Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.310+05:30
2024-12-07T10:03:22.310Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
2024-12-07T15:33:22.312+05:30
2024-12-07T10:03:22.312Z 1cb6467a-63e1-41ce-8378-b57b1c365069 INFO User Query Data :: { cursor: 9283678325492940000, keys: [] }
Activity