I am developing software in an embedded system (512 MB RAM). I'm using redis to take the place of a shared memory between processes inside a django application. We are talking about 150 values, stored every second, coming from a MODBUS device. They all have the same key and their expire time is 10 minutes. After some work hours (tipically a day), redis ceases to function, due to memory problems. Can someone help me out?
output of ps aux | grep redis
redis 1934 1.9 2.2 76216 8400 ? Ssl 07:49 10:37 /usr/bin/redis-server 127.0.0.1:6379
redis.info
# Server
redis_version:2.8.6
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:7cc01333adfd1c61
redis_mode:standalone
os:Linux 3.4.79+ armv7l
arch_bits:32
multiplexing_api:epoll
gcc_version:4.6.3
process_id:1934
run_id:be418b5a05b6670bb4bff9c73cc7126589d6b5c8
tcp_port:6379
uptime_in_seconds:33584
uptime_in_days:0
hz:10
lru_clock:858206
config_file:/etc/redis/redis.conf
# Clients
connected_clients:138
client_longest_output_list:54
client_biggest_input_buf:0
blocked_clients:0
# Memory
used_memory:6893800
used_memory_human:6.57M
used_memory_rss:6152192
used_memory_peak:47902480
used_memory_peak_human:45.68M
used_memory_lua:25600
mem_fragmentation_ratio:0.89
mem_allocator:jemalloc-3.0.0
# Persistence
loading:0
rdb_changes_since_last_save:1370469
rdb_bgsave_in_progress:0
rdb_last_save_time:1434611837
rdb_last_bgsave_status:ok
rdb_last_bgsave_time_sec:-1
rdb_current_bgsave_time_sec:-1
aof_enabled:0
aof_rewrite_in_progress:0
aof_rewrite_scheduled:0
aof_last_rewrite_time_sec:-1
aof_current_rewrite_time_sec:-1
aof_last_bgrewrite_status:ok
aof_last_write_status:ok
# Stats
total_connections_received:155
total_commands_processed:3207775
instantaneous_ops_per_sec:55
rejected_connections:0
sync_full:0
sync_partial_ok:0
sync_partial_err:0
expired_keys:297
evicted_keys:0
keyspace_hits:2141758
keyspace_misses:12495
pubsub_channels:6
pubsub_patterns:0
latest_fork_usec:0
# Replication
role:master
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
# CPU
used_cpu_sys:295.85
used_cpu_user:333.85
used_cpu_sys_children:0.00
used_cpu_user_children:0.00
# Keyspace
db0:keys=2,expires=2,avg_ttl=3185003
db1:keys=937,expires=242,avg_ttl=585637
snippet of redis-server.log
[1969] 18 Jun 22:17:21.819 # Server started, Redis version 2.8.6
[1969] 18 Jun 22:17:21.919 * DB loaded from disk: 0.100 seconds
[1969] 18 Jun 22:17:21.919 * The server is now ready to accept connections on port 6379
[1969] 18 Jun 22:17:21.919 * The server is now ready to accept connections at /var/run/redis/redis.sock
[1969] 19 Jun 09:16:50.444 # Client addr=127.0.0.1:38745 fd=9 name= age=39516 idle=4330 flags=N db=0 sub=1 psub=0 multi=-1 qbuf=0 qbuf-free=0 obl=13724 oll=415 omem=8509160 events=rw cmd=subscribe scheduled to be closed ASAP for overcoming of output buffer limits.
[1969] 19 Jun 09:20:54.056 # Client addr=127.0.0.1:38759 fd=14 name= age=4713 idle=4331 flags=N db=0 sub=1 psub=0 multi=-1 qbuf=0 qbuf-free=0 obl=13688 oll=415 omem=8509160 events=rw cmd=subscribe scheduled to be closed ASAP for overcoming of output buffer limits.
[1941] 19 Jun 09:17:17.134 # Unable to set the max number of files limit to 10032 (Operation not permitted), setting the max clients configuration to 3984.
Some lines from redis-cli monitor, if someone finds that useful. Being the same keys rewritten over and over again, it puzzles me with the high amount of memory used and all those files descriptors.