After you enable the QPS throttling feature, you may receive THROTTLED errors if requests to an instance exceed the specified threshold. This topic provides code examples for implementing a retry strategy to handle these errors.
Jedis
This example uses Jedis version 5.2.0.
Retry parameters
| Parameter | Value | Description |
|---|---|---|
MAX_RETRY |
10 | Maximum retry attempts before throwing the exception |
| Initial backoff | 2 s | Wait time before the first retry (2¹ seconds) |
| Backoff multiplier | 2x | Each subsequent retry doubles the wait: 2 s, 4 s, 8 s, ... |
| Retried error | THROTTLED |
Only THROTTLED errors are retried; all other errors propagate immediately |
Maven dependency
<!-- This example uses version 5.2.0. -->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>5.2.0</version>
</dependency>
Code sample
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
import redis.clients.jedis.exceptions.JedisException;
public class JedisThrottledTest {
private static final Logger logger = LoggerFactory.getLogger(JedisThrottledTest.class);
private static final int MAX_RETRY = 10; // Maximum retry attempts
public static void main(String[] args) {
if (args.length < 3) {
System.out.println("Usage: java -jar JedisThrottledTest.jar <host> <port> <password>");
return;
}
String host = args[0];
int port = Integer.parseInt(args[1]);
String password = args[2];
JedisPoolConfig poolConfig = new JedisPoolConfig();
poolConfig.setMaxTotal(32);
poolConfig.setMaxIdle(32);
poolConfig.setMinIdle(16);
JedisPool jedisPool = new JedisPool(poolConfig, host, port, 3000, password);
for (int i = 0; i < 4; i++) {
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < Integer.MAX_VALUE; i++) {
executeWithRetry(jedisPool, "key" + i, "value" + i);
}
}
}).start();
}
}
private static void executeWithRetry(JedisPool jedisPool, String key, String value) {
int retryCount = 0;
while (retryCount < MAX_RETRY) {
try (Jedis jedis = jedisPool.getResource()) {
jedis.set(key, value);
break;
} catch (JedisException e) {
if (e.getMessage().contains("THROTTLED")) {
logger.info("Throttled error occurred (attempt " + retryCount + "): " + e.getMessage());
retryCount++;
if (retryCount >= MAX_RETRY) {
logger.info("Max retry attempts reached.");
throw e;
}
try {
int sleepTime = (int)Math.pow(2, retryCount);
Thread.sleep(sleepTime * 1000);
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
throw new RuntimeException("Thread interrupted during retry delay", ie);
}
} else {
throw e;
}
}
}
}
}
Valkey-java
Important
Use valkey-java version 5.4.0 or later.
Retry parameters
| Parameter | Value | Description |
|---|---|---|
maxAttempts |
100 | Maximum retry attempts |
maxTotalRetriesDuration |
1,000 s | Maximum total time spent on retries |
| Initial backoff | 1 s | Wait time before the first retry (2⁰ seconds) |
| Backoff multiplier | 2x | Each subsequent retry doubles the wait: 1 s, 2 s, 4 s, ... |
| Retried error | THROTTLED |
Only messages containing THROTTLED trigger the backoff callback |
Maven dependency
<dependency>
<groupId>io.valkey</groupId>
<artifactId>valkey-java</artifactId>
<version>5.4.0</version>
</dependency>
Code sample
The ExceptionHandler in Valkey-java lets you register callbacks for specific error patterns. This example registers an exponential backoff callback for THROTTLED errors, so the retry logic is separate from your application code.
import java.time.Duration;
import io.valkey.DefaultJedisClientConfig;
import io.valkey.ExceptionHandler;
import io.valkey.HostAndPort;
import io.valkey.UnifiedJedis;
import io.valkey.providers.PooledConnectionProvider;
import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ThrottledTest {
private static final Logger logger = LoggerFactory.getLogger(ThrottledTest.class);
/**
* Implements exponential backoff.
*/
static class ExponentialBackoffCallback implements ExceptionHandler.ErrorCallback {
private int attempt = 0;
@Override
public void onError(String errorMessage) {
int sleepTime = (int)Math.pow(2, attempt);
try {
logger.info("Sleeping for " + sleepTime + " seconds before handling: " + errorMessage);
Thread.sleep(sleepTime * 1000);
} catch (InterruptedException ie) {
// Ignore the error.
}
attempt++;
}
}
public static void main(String[] args) {
if (args.length < 3) {
System.out.println("Usage: java -jar ThrottledTest.jar <host> <port> <password>");
return;
}
String host = args[0];
int port = Integer.parseInt(args[1]);
String password = args[2];
GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
poolConfig.setMaxTotal(32);
poolConfig.setMaxIdle(32);
poolConfig.setMinIdle(16);
int maxAttempts = 100; // Maximum retry attempts
Duration maxTotalRetriesDuration = Duration.ofSeconds(1000); // Maximum total duration for retries
PooledConnectionProvider provider = new PooledConnectionProvider(new HostAndPort(host, port),
DefaultJedisClientConfig.builder().password(password).build(), poolConfig);
ExceptionHandler handler = new ExceptionHandler();
handler.register(
message -> message.contains("THROTTLED"),
new ExponentialBackoffCallback()
);
UnifiedJedis unifiedJedis = new UnifiedJedis(provider, maxAttempts, maxTotalRetriesDuration, handler);
for (int i = 0; i < 4; i++) { // Use four threads to generate high QPS.
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < Integer.MAX_VALUE; i++) {
try {
unifiedJedis.set("" + i, "" + i);
} catch (Exception e) {
logger.error("Error occurred {}", e.getMessage());
}
}
}
}).start();
}
}
}
redis-py
This example uses redis-py version 6.1.1.
Retry parameters
| Parameter | Value | Description |
|---|---|---|
MAX_RETRY |
10 | Maximum retry attempts before raising the exception |
| Initial backoff | 2 s | Wait time before the first retry (2¹ seconds) |
| Backoff multiplier | 2x | Each subsequent retry doubles the wait: 2 s, 4 s, 8 s, ... |
socket_timeout |
3 s | Connection timeout |
| Retried error | THROTTLED |
Only THROTTLED errors are retried; all other RedisError exceptions propagate immediately |
Code sample
import sys
import time
import threading
import logging
from redis import Redis, RedisError
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)
MAX_RETRY = 10 # Maximum retry attempts
def execute_with_retry(redis_client, key, value):
retry_count = 0
while retry_count < MAX_RETRY:
try:
redis_client.set(key, value)
break # If successful, exit the loop.
except RedisError as e:
if "THROTTLED" in str(e):
logger.info(f"Throttled error occurred (attempt {retry_count}): {e}")
retry_count += 1
if retry_count >= MAX_RETRY:
logger.info("Max retry attempts reached.")
raise e
sleep_time = 2 ** retry_count
time.sleep(sleep_time)
else:
logger.error(f"Non-throttled Redis error: {e}")
raise e
def worker(redis_client):
i = 0
while True:
try:
execute_with_retry(redis_client, f"key{i}", f"value{i}")
i += 1
except Exception as e:
logger.exception(f"Unexpected error in worker: {e}")
time.sleep(1) # Avoid tight loop in case of persistent errors
def main():
if len(sys.argv) < 4:
print("Usage: python script.py <host> <port> <password>")
return
host = sys.argv[1]
port = int(sys.argv[2])
password = sys.argv[3]
redis_client = Redis(
host=host,
port=port,
password=password,
socket_timeout=3,
decode_responses=True
)
# Test the connection.
try:
redis_client.ping()
logger.info("Successfully connected to Redis")
except RedisError as e:
logger.error(f"Failed to connect to Redis: {e}")
return
# Create and start 10 threads.
threads = []
for i in range(10):
thread = threading.Thread(target=worker, args=(redis_client,))
thread.daemon = True
thread.start()
threads.append(thread)
logger.info(f"Started worker thread {i}")
# Keep the main thread running.
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
logger.info("Program interrupted. Exiting...")
# Wait for all threads to complete.
for thread in threads:
thread.join()
if __name__ == "__main__":
main()