Infinite loop of "unable to schedule timer" when cyc... | dfinity/cdk-rs

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If the canister does not have enough cycles to schedule a timer (or interval), the library ends up in what is effectively an infinite loop of reattempts:

Canister logs

[7359. 2026-04-01T07:07:55.841725127Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7360. 2026-04-01T07:07:56.25502391Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7361. 2026-04-01T07:07:56.723303182Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7362. 2026-04-01T07:07:57.144843964Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7363. 2026-04-01T07:07:57.488891711Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7364. 2026-04-01T07:07:57.963775576Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7365. 2026-04-01T07:07:58.346957392Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7366. 2026-04-01T07:07:58.767879228Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7367. 2026-04-01T07:07:59.228574857Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7368. 2026-04-01T07:07:59.642307946Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7369. 2026-04-01T07:08:00.004852977Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7370. 2026-04-01T07:08:00.418322193Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7371. 2026-04-01T07:08:00.85038844Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7372. 2026-04-01T07:08:01.252940375Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7373. 2026-04-01T07:08:01.675909951Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7374. 2026-04-01T07:08:02.084408966Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7375. 2026-04-01T07:08:02.501918417Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7376. 2026-04-01T07:08:02.906392949Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7377. 2026-04-01T07:08:03.314078906Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7378. 2026-04-01T07:08:03.745544949Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7379. 2026-04-01T07:08:04.160874185Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7380. 2026-04-01T07:08:04.560114921Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7381. 2026-04-01T07:08:04.979469778Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7382. 2026-04-01T07:08:05.400479551Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7383. 2026-04-01T07:08:05.814826355Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7384. 2026-04-01T07:08:06.293797354Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7385. 2026-04-01T07:08:06.694427817Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7386. 2026-04-01T07:08:07.13025302Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles
[7387. 2026-04-01T07:08:07.546944138Z]: [ic-cdk-timers] unable to schedule timer: not enough liquid cycles

Reproduction steps

Schedule a timer
Wait for cycles to drain
Watch the logs

Start by tracing the ic-cdk-timers scheduling path responsible for the repeated “unable to schedule timer” log when liquid cycles are insufficient. Reproduce the issue by scheduling a timer and allowing cycles to drain, then verify that the retry behavior no longer produces an effectively infinite stream of attempts.

Written by the indexing model from the issue text.

Infinite loop of "unable to schedule timer" when cycles run low

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Assessment