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transport: Fix pending dials memory leak #271

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merged 2 commits into from
Oct 24, 2024
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@lexnv lexnv commented Oct 22, 2024

The pending_dials is populated with a connection ID when initiating outbound connections.
The state is rightfully cleaned up when the dialing fails, and error propagated back to the user.
However, the state was not cleared when the dialing succeeded. This was leading to a subtle memory leak in litep2p.

Testing Done

I used a custom-patched version of litep2p to log the number of pending dials. After a few hours, the pending dials for both TCP and WebSocket connections stabilized at just a few.

2024-10-22 17:37:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=1 pending_inbound_connections=0 pending_connections=1 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:38:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=1 opened_raw=0 cancel_futures=1 pending_open=0
2024-10-22 17:38:56.253  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:39:26.253  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:39:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:40:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=1 opened_raw=0 cancel_futures=1 pending_open=0
2024-10-22 17:40:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:41:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0

Closes: #269

Signed-off-by: Alexandru Vasile <[email protected]>
@lexnv lexnv merged commit e378e76 into master Oct 24, 2024
8 checks passed
@lexnv lexnv deleted the lexnv/fix-manager-leak branch October 24, 2024 15:51
lexnv added a commit that referenced this pull request Oct 30, 2024
This fixes a bug in the TCP and Websocket transports that was leaking
memory for:
- `canceled: HashSet<ConnectionId>` - leak since the beginning of
litep2p
- `cancel_futures: HashMap<ConnectionId, AbortHandle>` added in unmerged
#255


The memory leak is happening in the following scenarios:
- T0: transport manager: dials K (parallelism factor = 8) addresses on
TCP and WebSocket on ConnectionId=1
- T1: TCP: establishes a connection with the peer ConnectionId=1
- T2: WebSocket: establishes a connection with the peer ConnectionId=1
- T3: transport manager: receives TCP establishment event and cancels
`WebSocket` dials
 
The issue happens when T2 finishes before T3.
In this situation, the WebSocket transport no longer has a future with a
corresponding ConnectionId=1.
The canceling method simply inserts ConnectionId=1 into a hashset This
leads to the hashset growing over time, without a way to clean-up stale
connection IDs.


The fix relies on the changes added in
#255:
- `cancel_futures` maps a connection ID to an abort handle
- the `cancel_futures` is guaranteed to contain a connection ID that
corresponds to an unfinished `pending_raw_connections` future
- the cancel method just aborts the in-flight future, if it exists
- state of the `cancel_futures` is done when polling
`pending_raw_connections`

### Testing Done

I used a custom-patched version of litep2p to log the number of pending
dials. After a few hours, the pending dials for both TCP and WebSocket
connections stabilized at just a few. (Same as
#271).

```
2024-10-22 17:37:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=1 pending_inbound_connections=0 pending_connections=1 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:38:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=1 opened_raw=0 cancel_futures=1 pending_open=0
2024-10-22 17:38:56.253  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:39:26.253  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:39:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:40:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=1 opened_raw=0 cancel_futures=1 pending_open=0
2024-10-22 17:40:56.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
2024-10-22 17:41:26.252  INFO tokio-runtime-worker litep2p::tcp: status pending_dials=0 pending_inbound_connections=0 pending_connections=0 pending_raw_connections=0 opened_raw=0 cancel_futures=0 pending_open=0
```


Build on: #255

Closes: #270

---------

Signed-off-by: Alexandru Vasile <[email protected]>
Co-authored-by: Dmitry Markin <[email protected]>
lexnv added a commit that referenced this pull request Nov 4, 2024
## [0.8.0] - 2024-11-01

This release adds support for content provider advertisement and
discovery to Kademlia protocol implementation (see libp2p
[spec](https://github.com/libp2p/specs/blob/master/kad-dht/README.md#content-provider-advertisement-and-discovery)).
Additionally, the release includes several improvements and memory leak
fixes to enhance the stability and performance of the litep2p library.

### Added

- kad: Providers part 8: unit, e2e, and `libp2p` conformance tests
([#258](#258))
- kad: Providers part 7: better types and public API, public addresses &
known providers ([#246](#246))
- kad: Providers part 6: stop providing
([#245](#245))
- kad: Providers part 5: `GET_PROVIDERS` query
([#236](#236))
- kad: Providers part 4: refresh local providers
([#235](#235))
- kad: Providers part 3: publish provider records (start providing)
([#234](#234))

### Changed

- transport_service: Improve connection stability by downgrading
connections on substream inactivity
([#260](#260))
- transport: Abort canceled dial attempts for TCP, WebSocket and Quic
([#255](#255))
- kad/executor: Add timeout for writting frames
([#277](#277))
- kad: Avoid cloning the `KademliaMessage` and use reference for
`RoutingTable::closest`
([#233](#233))
- peer_state: Robust state machine transitions
([#251](#251))
- address_store: Improve address tracking and add eviction algorithm
([#250](#250))
- kad: Remove unused serde cfg
([#262](#262))
- req-resp: Refactor to move functionality to dedicated methods
([#244](#244))
- transport_service: Improve logs and move code from tokio::select macro
([#254](#254))

### Fixed

- tcp/websocket/quic: Fix cancel memory leak
([#272](#272))
- transport: Fix pending dials memory leak
([#271](#271))
- ping: Fix memory leak of unremoved `pending_opens`
([#274](#274))
- identify: Fix memory leak of unused `pending_opens`
([#273](#273))
- kad: Fix not retrieving local records
([#221](#221))

---------

Signed-off-by: Alexandru Vasile <[email protected]>
Co-authored-by: Dmitry Markin <[email protected]>
github-merge-queue bot pushed a commit to paritytech/polkadot-sdk that referenced this pull request Nov 5, 2024
This PR updates litep2p to the latest release.

- `KademliaEvent::PutRecordSucess` is renamed to fix word typo
- `KademliaEvent::GetProvidersSuccess` and
`KademliaEvent::IncomingProvider` are needed for bootnodes on DHT work
and will be utilized later


### Added

- kad: Providers part 8: unit, e2e, and `libp2p` conformance tests
([#258](paritytech/litep2p#258))
- kad: Providers part 7: better types and public API, public addresses &
known providers ([#246](paritytech/litep2p#246))
- kad: Providers part 6: stop providing
([#245](paritytech/litep2p#245))
- kad: Providers part 5: `GET_PROVIDERS` query
([#236](paritytech/litep2p#236))
- kad: Providers part 4: refresh local providers
([#235](paritytech/litep2p#235))
- kad: Providers part 3: publish provider records (start providing)
([#234](paritytech/litep2p#234))

### Changed

- transport_service: Improve connection stability by downgrading
connections on substream inactivity
([#260](paritytech/litep2p#260))
- transport: Abort canceled dial attempts for TCP, WebSocket and Quic
([#255](paritytech/litep2p#255))
- kad/executor: Add timeout for writting frames
([#277](paritytech/litep2p#277))
- kad: Avoid cloning the `KademliaMessage` and use reference for
`RoutingTable::closest`
([#233](paritytech/litep2p#233))
- peer_state: Robust state machine transitions
([#251](paritytech/litep2p#251))
- address_store: Improve address tracking and add eviction algorithm
([#250](paritytech/litep2p#250))
- kad: Remove unused serde cfg
([#262](paritytech/litep2p#262))
- req-resp: Refactor to move functionality to dedicated methods
([#244](paritytech/litep2p#244))
- transport_service: Improve logs and move code from tokio::select macro
([#254](paritytech/litep2p#254))

### Fixed

- tcp/websocket/quic: Fix cancel memory leak
([#272](paritytech/litep2p#272))
- transport: Fix pending dials memory leak
([#271](paritytech/litep2p#271))
- ping: Fix memory leak of unremoved `pending_opens`
([#274](paritytech/litep2p#274))
- identify: Fix memory leak of unused `pending_opens`
([#273](paritytech/litep2p#273))
- kad: Fix not retrieving local records
([#221](paritytech/litep2p#221))

See release changelog for more details:
https://github.com/paritytech/litep2p/releases/tag/v0.8.0

cc @paritytech/networking

---------

Signed-off-by: Alexandru Vasile <[email protected]>
Co-authored-by: Dmitry Markin <[email protected]>
lexnv added a commit to paritytech/polkadot-sdk that referenced this pull request Nov 15, 2024
This PR updates litep2p to the latest release.

- `KademliaEvent::PutRecordSucess` is renamed to fix word typo
- `KademliaEvent::GetProvidersSuccess` and
`KademliaEvent::IncomingProvider` are needed for bootnodes on DHT work
and will be utilized later

- kad: Providers part 8: unit, e2e, and `libp2p` conformance tests
([#258](paritytech/litep2p#258))
- kad: Providers part 7: better types and public API, public addresses &
known providers ([#246](paritytech/litep2p#246))
- kad: Providers part 6: stop providing
([#245](paritytech/litep2p#245))
- kad: Providers part 5: `GET_PROVIDERS` query
([#236](paritytech/litep2p#236))
- kad: Providers part 4: refresh local providers
([#235](paritytech/litep2p#235))
- kad: Providers part 3: publish provider records (start providing)
([#234](paritytech/litep2p#234))

- transport_service: Improve connection stability by downgrading
connections on substream inactivity
([#260](paritytech/litep2p#260))
- transport: Abort canceled dial attempts for TCP, WebSocket and Quic
([#255](paritytech/litep2p#255))
- kad/executor: Add timeout for writting frames
([#277](paritytech/litep2p#277))
- kad: Avoid cloning the `KademliaMessage` and use reference for
`RoutingTable::closest`
([#233](paritytech/litep2p#233))
- peer_state: Robust state machine transitions
([#251](paritytech/litep2p#251))
- address_store: Improve address tracking and add eviction algorithm
([#250](paritytech/litep2p#250))
- kad: Remove unused serde cfg
([#262](paritytech/litep2p#262))
- req-resp: Refactor to move functionality to dedicated methods
([#244](paritytech/litep2p#244))
- transport_service: Improve logs and move code from tokio::select macro
([#254](paritytech/litep2p#254))

- tcp/websocket/quic: Fix cancel memory leak
([#272](paritytech/litep2p#272))
- transport: Fix pending dials memory leak
([#271](paritytech/litep2p#271))
- ping: Fix memory leak of unremoved `pending_opens`
([#274](paritytech/litep2p#274))
- identify: Fix memory leak of unused `pending_opens`
([#273](paritytech/litep2p#273))
- kad: Fix not retrieving local records
([#221](paritytech/litep2p#221))

See release changelog for more details:
https://github.com/paritytech/litep2p/releases/tag/v0.8.0

cc @paritytech/networking

---------

Signed-off-by: Alexandru Vasile <[email protected]>
Co-authored-by: Dmitry Markin <[email protected]>
Signed-off-by: Alexandru Vasile <[email protected]>
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TCP/WebSocket: Fix memory leak of pending dials
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