Redis java.net.SocketTimeoutException: Read timed out on setting value while High memory utilization on redis cluster - caching

Question

I am using Jedis client for redis in my spring service.
Below is the similar code which I use for setting value into a hashedkey.
Jedis jedis = null;
try {
1-- jedis = redisJedisPool.getResource();
2-- jedis.hset(key,"data", dataValue);
for (Entry<String, String> entry : hmap.entrySet()) {
if (some condition)
3-- jedis.hset(key, entry.getKey(), entry.getValue());
}
4-- jedis.expire(key, ttl);
}catch(Exception e) {
logger.error("Error for key {}, Reason: {}", key, e.getMessage());
}
finally {
RedisConnectionManager.closeJedisResource(jedis);
}
there was heavy load on this service and thus a high memory utilization of the redis cluster was noticed.
I faced a lot of SocketTimeoutException from the above function(all exception where catched in the catch block).
Exception:
Error for key: {key}, Reason: java.net.SocketTimeoutException: Read timed out
Main Issue: After this intermittent issue I see a lot of keys with ttl as -1(infinite expiry). Almost all these keys where logged in the above catch block.
Need thoughts on this from the community on what can be the possible issue here.
Action I took for verifying: I checked the data for few of these keys(with ttl -1) and saw that the data that was to be set at line 3(inside the for loop) didn't set all the data. But I came across couple of keys which had ttl as -1, not all data was set but that key was not logged in the above catch block. And this is the only func where the setting of data in cache takes place in my service.
After this I am not able to conclude the above hypothesis.