Fix memory leak of jemalloc tcache on function flush command #13661
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Co-authored-by: debing.sun <debing.sun@redis.com>
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tezc
commented
Nov 21, 2024
| unsigned int lua_tcache = (unsigned int)(uintptr_t)ud; | ||
| #endif | ||
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| lua_close(lua); |
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moved down this call not to access its ud field after lua_close().
sundb
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Nov 21, 2024
oranagra
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Nov 21, 2024
YaacovHazan
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Apr 22, 2025
…3661) Starting from redis#13133, we allocate a jemalloc thread cache and use it for lua vm. On certain cases, like `script flush` or `function flush` command, we free the existing thread cache and create a new one. Though, for `function flush`, we were not actually destroying the existing thread cache itself. Each call creates a new thread cache on jemalloc and we leak the previous thread cache instances. Jemalloc allows maximum 4096 thread cache instances. If we reach this limit, Redis prints "Failed creating the lua jemalloc tcache" log and abort. There are other cases that can cause this memory leak, including replication scenarios when emptyData() is called. The implication is that it looks like redis `used_memory` is low, but `allocator_allocated` and RSS remain high. Co-authored-by: debing.sun <debing.sun@redis.com>
funny-dog
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Sep 17, 2025
…3661) Starting from redis#13133, we allocate a jemalloc thread cache and use it for lua vm. On certain cases, like `script flush` or `function flush` command, we free the existing thread cache and create a new one. Though, for `function flush`, we were not actually destroying the existing thread cache itself. Each call creates a new thread cache on jemalloc and we leak the previous thread cache instances. Jemalloc allows maximum 4096 thread cache instances. If we reach this limit, Redis prints "Failed creating the lua jemalloc tcache" log and abort. There are other cases that can cause this memory leak, including replication scenarios when emptyData() is called. The implication is that it looks like redis `used_memory` is low, but `allocator_allocated` and RSS remain high. Co-authored-by: debing.sun <debing.sun@redis.com>
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Starting from #13133, we allocate a jemalloc thread cache and use it for lua vm.
On certain cases, like
script flushorfunction flushcommand, we free the existing thread cache and create a new one.Though, for
function flush, we were not actually destroying the existing thread cache itself. Each call creates a new thread cache on jemalloc and we leak the previous thread cache instances. Jemalloc allows maximum 4096 thread cache instances. If we reach this limit, Redis prints "Failed creating the lua jemalloc tcache" log and abort.There are other cases that can cause this memory leak, including replication scenarios when emptyData() is called.
The implication is that it looks like redis
used_memoryis low, butallocator_allocatedand RSS remain high.