Iterating a range of skipmap and insert back may cause mem leak

[jingnz25]

crossbeam-skiplist = "0.1.3"

iter range from skipmap, clone (key, value)s and insert back to skipmap

Code:

use crossbeam_skiplist::SkipMap;

fn main() {
    let map = SkipMap::new();
    let _ = map.insert(vec![1u8], vec![1u8]);
    let _ = map.insert(vec![2], vec![2]);
    let _ = map.insert(vec![3], vec![3]);

    let kvs: Vec<(Vec<u8>, Vec<u8>)> = map
        .range(vec![1]..vec![3])
        .map(|e| (e.key().clone(), e.value().clone()))
        .collect();

    for (k, v) in kvs {
        map.insert(k, v);
    }
}

Run with address sanitizer:

RUSTFLAGS='-Z sanitizer=address' cargo run
   Compiling crossbeam-utils v0.8.21
   Compiling crossbeam-epoch v0.9.18
   Compiling crossbeam-skiplist v0.1.3
   Compiling test-skipmap v0.1.0 (/data/rust/test-skipmap)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.19s
     Running `target/debug/test-skipmap`

=================================================================
==1738483==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 64 byte(s) in 1 object(s) allocated from:
    #0 0x55db3995997f  (/data/rust/test-skipmap/target/debug/test-skipmap+0x9997f) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #1 0x55db39990faf  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd0faf) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #2 0x55db3999444e  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd444e) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #3 0x55db3999806f  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd806f) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #4 0x55db3998e3a9  (/data/rust/test-skipmap/target/debug/test-skipmap+0xce3a9) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #5 0x55db3998a5ca  (/data/rust/test-skipmap/target/debug/test-skipmap+0xca5ca) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #6 0x55db3998f8aa  (/data/rust/test-skipmap/target/debug/test-skipmap+0xcf8aa) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #7 0x55db399c7191  (/data/rust/test-skipmap/target/debug/test-skipmap+0x107191) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #8 0x55db39983dd8  (/data/rust/test-skipmap/target/debug/test-skipmap+0xc3dd8) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #9 0x55db3998af5d  (/data/rust/test-skipmap/target/debug/test-skipmap+0xcaf5d) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)

Indirect leak of 2 byte(s) in 2 object(s) allocated from:
    #0 0x55db3995997f  (/data/rust/test-skipmap/target/debug/test-skipmap+0x9997f) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #1 0x55db39990faf  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd0faf) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #2 0x55db39991240  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd1240) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #3 0x55db39990dea  (/data/rust/test-skipmap/target/debug/test-skipmap+0xd0dea) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #4 0x55db3998f8aa  (/data/rust/test-skipmap/target/debug/test-skipmap+0xcf8aa) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #5 0x55db399c7191  (/data/rust/test-skipmap/target/debug/test-skipmap+0x107191) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #6 0x55db39983dd8  (/data/rust/test-skipmap/target/debug/test-skipmap+0xc3dd8) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)
    #7 0x55db3998af5d  (/data/rust/test-skipmap/target/debug/test-skipmap+0xcaf5d) (BuildId: 605573717e3f8eea538fe0d266711226d7071a30)

SUMMARY: AddressSanitizer: 66 byte(s) leaked in 3 allocation(s).

[taiki-e]

Thanks for the report! I wonder if this is the same issue as #540...

[jingnz25]

Actually in my program there is a SkipMap in tokio RwLock, I spawned two threads do some operations in loop, one thread insert kvs to map, and clear map after every 100 insertions, another thread call range and clone kvs from map, then insert back to map. I observed a continuous memory increase while running the program.

I'm wodering why memory stays stable when I call iter instead of range in the above situation. And should I call crossbeam_epoch::pin().flush() after every operation?