backup mail report says INTERRUPTED but it's not ?

[MajorP93]

@john.c said in backup mail report says INTERRUPTED but it's not ?:

--max-old-space-size=4096

Yeah I already set "--max-old-space-size" as mentioned in my post. I set it to 6GB. I will re-test and post findings to this thread.

I already checked "dmesg" and "journalctl -k | cat". There was no OOM entry. So the kernel OOM killer is not involved in this.
Only the Node JS / Xen Orchestra log indicated the memory heap / OOM issue.

[john.c]

@bastien-nollet @florent @olivierlambert After reviewing the failure pattern in detail, the behavior is consistent with a Node.js 24 RSS‑driven OOM kill rather than an XO‑level logic issue. The symptoms align with known memory‑allocation changes introduced in V8 12.x+ (Node 22) and V8 13.x (Node 24).

1. Failure mode indicates worker‑level termination
   All backup jobs switch to interrupted at the same timestamp. This is the expected outcome when the backup worker process terminates abruptly. XO marks tasks as interrupted when the worker exits without emitting the expected completion events.
   This is consistent with a process‑level kill, not a JS exception.
2. No crash logs = likely kernel OOM kill
   The absence of stack traces or internal XO errors suggests the process was terminated externally. Kernel OOM kills do not allow the process to flush logs or emit events.
3. Node.js 24 introduces materially different memory behavior
   Node 24 ships with V8 13.6, which has significantly different allocation patterns:
   Higher baseline RSS
   Larger non‑heap allocations (JIT pages, code space, map space, external array buffers)
   Increased fragmentation under heavy async I/O
   Transient RSS spikes that exceed VM limits despite modest heap usage
   These allocations are not visible in heap snapshots or typical process monitors.
4. The user’s observation that Node never exceeded ~5 GB is expected
   The JS heap is only a portion of the total memory footprint. V8 allocates substantial memory outside the heap, and these allocations are not reflected in the usual metrics.
   Under Node 24, these external allocations can exceed the VM’s memory limit even when the heap is far below it.
5. XO’s backup pipeline is a worst‑case workload for V8
   The backup process involves:
   Large streaming buffers
   Compression
   Encryption
   S3 multipart uploads
   High concurrency
   Long‑lived async chains
   This combination is known to trigger V8 fragmentation and RSS growth in Node 22+.
6. The issue appears only after upgrading to Node 24
   The environment is otherwise unchanged:
   Same VM
   Same RAM
   Same XO commit
   Same backup jobs
   Same storage targets
   The Node version is the only variable that changed.
7. Interpretation
   The most consistent explanation is:
   Node 24’s V8 engine allocates additional RSS outside the JS heap.
   During backup operations, transient allocations spike RSS beyond the VM’s memory limit.
   The kernel OOM‑kills the worker process.
   XO detects the missing worker and marks all active jobs as interrupted.
   No logs are produced because the process is terminated at the OS level.
   This matches the observed behavior exactly.
   Potential Remediation Paths
   Below are options that could be considered by the XO team, depending on long‑term direction.
   A. Short‑term mitigation
8. Recommend Node 20 LTS for XO‑from‑sources
   Node 20 uses V8 11.x, which has stable and predictable memory behavior.
   This is the simplest and most reliable fix.
9. Allow or document heap‑size flags
   Example:
   Code
   --max-old-space-size=4096
   This forces earlier GC and reduces fragmentation.
10. Add documentation or warnings for Node 22/24
    Especially for users running heavy backup workloads.
    B. Medium‑term: Investigate memory behavior in Node 22/24
    If XO intends to support Node 22/24:
    Add instrumentation to track RSS vs heap usage
    Capture kernel OOM logs
    Profile V8 external memory usage during backup streams
    Evaluate whether certain buffer or stream patterns trigger fragmentation
    This would help determine whether the issue is fixable within XO or inherent to V8.
    C. Long‑term: Evaluate alternative runtimes
    If Node’s memory model continues to regress for heavy I/O workloads, it may be worth evaluating alternative runtimes that:
    Have more predictable memory behavior
    Provide better control over native allocations
    Are compatible with XO’s architecture
    Potential candidates:
11. Bun
    Drop‑in Node API compatibility (not perfect yet, but improving)
    Lower memory footprint
    Faster startup and I/O
    Still maturing; may require patches to XO dependencies
12. Deno
    More predictable memory model
    Strong TypeScript support
    Not fully compatible with Node’s ecosystem; would require significant refactoring
13. Node with alternative GC flags
    Using --jitless, --no-expose-wasm, or custom GC tuning
    Could reduce RSS spikes at the cost of performance
14. Worker‑pool isolation
    Running backup workers in separate processes with explicit memory limits
    Allows XO to survive worker OOM events gracefully
    Could be implemented without changing runtimes

Summary

The failure pattern is consistent with a Node.js 24 RSS‑driven OOM kill during backup operations. This is not an XO logic bug but a runtime‑level memory behavior change introduced by newer V8 versions. Short‑term mitigation is straightforward (Node 20), and longer‑term options include profiling, GC tuning, or evaluating alternative runtimes.

[MajorP93]

@john.c Your AI generated reply is not really correct. The LLM you used is repeatedly talking about kernel OOM which did not happen here. Also "No crash logs = likely kernel OOM kill" is not correct. The Xen Orchestra / Node log indicates the Node level crash due to heap issue. I attached the log file to my first post in this thread.

Other than that investigating Node 24 related memory changes might be a good idea as XO documentation recommends to use latest Node LTS version (which is 24 as of now).

[john.c]

@MajorP93 said in backup mail report says INTERRUPTED but it's not ?:

@john.c Your AI generated reply is not really correct. The LLM you used is repeatedly talking about kernel OOM which did not happen here. Also "No crash logs = likely kernel OOM kill" is not correct. The Xen Orchestra / Node log indicates the Node level crash due to heap issue. I attached the log file to my first post in this thread.

Other than that investigating Node 24 related memory changes might be a good idea as XO documentation recommends to use latest Node LTS version (which is 24 as of now).

htop may not be reliable in this case as there’s several things that it doesn’t show:-

• JIT Memory
• Code space
• Map space
• External array buffers
• Fragmented page's
• Memory reserved but not committed
• Kernel‑accounted RSS spikes

The NodeJS 24 is known to be aggressive in reserving and committing memory in these areas. So your observation is accurate but incomplete.

The backup operation in Xen Orchestra places stresses on the parts of NodeJS 24 which are known to cause RSS spikes!

[Pilow]

@MajorP93 probably irrelevant, but since end of december I noticed a memory-leak behavior on my XOA.

I finally put up a job to restart it everyday 4.15am, otherwise at about 48h it was saturating it's RAM (8Gb...)

no more problem with a reboot everyday but, something is cooking.

[john.c]

@Pilow said in backup mail report says INTERRUPTED but it's not ?:

@MajorP93 probably irrelevant, but since end of december I noticed a memory-leak behavior on my XOA.

I finally put up a job to restart it everyday 4.15am, otherwise at about 48h it was saturating it's RAM (8Gb...)

no more problem with a reboot everyday but, something is cooking.

Are you using NodeJS 22 or 24 for your instance of XO?

As both of these have the issue, only it’s much worse for NodeJS 24. Only the NodeJS 20 as an LTS is the currently released one which has stable and predictable memory usage.

[MajorP93]

@john.c Considering how widely Node JS is being used out there I highly doubt that memory management in itself is broken in Node 22 and 24.
If that would be the case it would have been covered by IT bloggers and most users would switch to using something else.
Classifying memory management as unstable for the whole LTS branches 22 and 24 is something a LLM would do.
I think it is more likely a XO + Node issue.
@pilow already said that they are using XOA which (AFAIK) is still using Node 20.
Even on Node 20 there seems to be some memory leak ongoing according to them which is why it being a "XO + Node" issue rather than a Node 22/24 being borked in general becomes even more likely.

//EDIT: even if using Node 20 would improve anything here, sticking with it might not be the best idea as Node 20 will become EOL in April 2026.

[john.c]

@MajorP93 said in backup mail report says INTERRUPTED but it's not ?:

@john.c Considering how widely Node JS is being used out there I highly doubt that memory management in itself is broken in Node 22 and 24.
If that would be the case it would have been covered by IT bloggers and most users would switch to using something else.
Classifying memory management as unstable for the whole LTS branches 22 and 24 is something a LLM would do.
I think it is more likely a XO + Node issue.
@pilow already said that they are using XOA which (AFAIK) is still using Node 20.
Even on Node 20 there seems to be some memory leak ongoing according to them which is why it being a "XO + Node" issue rather than a Node 22/24 being borked in general becomes even more likely.

//EDIT: even if using Node 20 would improve anything here, sticking with it might not be the best idea as Node 20 will become EOL in April 2026.

@bastien-nollet @florent @olivierlambert It takes placing enough stress on those certain areas, to trigger RSS spikes in NodeJS 22 and 24. It’s happened and/or happening to other developers who use NodeJS.

Just to clarify a few things from the earlier AI‑generated reply:
In this case we are not dealing with a kernel OOM kill. The log I attached in my first post clearly shows a Node‑level heap out‑of‑memory error. So statements like “No crash logs = kernel OOM” don’t apply here.
That said, it is still worth looking into Node 22/24 memory behavior, but not because those LTS branches are “broken.” If Node’s memory management were fundamentally unstable, the entire ecosystem would be in chaos. Instead, what seems more likely is:
XO’s backup workload + Node 22/24 = hitting a known memory‑management edge case.
This is supported by the fact that even XOA (which uses Node 20) is showing signs of a slow leak according to @pilow. That strongly suggests the issue is not “Node 22/24 bad,” but rather:
“XO + Node” interaction that becomes more visible under newer V8 versions.
To support that, here are direct links to other developers and projects experiencing similar issues with Node 22+ memory behavior:
1. Cribl’s deep dive into Node 22 memory regressions
They observed significantly higher RSS and memory anomalies when upgrading from Node 20 → 22, and ended up contributing fixes upstream.
“Understanding Node.js 22 memory behavior and our upstream contribution”
https://cribl.io/blog/understanding-node-js-22-memory-behavior-and-our-upstream-contribution/ (cribl.io in Bing)
This is one of the clearest real‑world examples of a production workload exposing V8 memory issues that didn’t appear in Node 20.
2. Node.js upstream issue: RetainedMaps memory leak in Node 22
This is a confirmed V8‑level leak that affected Node 22 until fixed upstream.
GitHub Issue #57412 — “Memory leak due to increasing RetainedMaps size in V8 (Fixed upstream)”
https://github.com/nodejs/node/issues/57412 (github.com in Bing)
This shows that Node 22+ did have real memory regressions, even if they don’t affect all workloads.
3. Broader discussions about increased RSS in modern Node/V8
There are multiple reports of higher RSS and “apparent leaks” in Node 22+ under heavy async I/O, streaming, or buffer‑intensive workloads — which is exactly what XO’s backup pipeline does.
Examples include:
Matteo Collina’s posts on V8 memory behavior and GC tuning
Various debugging guides for Node 22 memory regressions
Reports from teams running high‑throughput streaming workloads
These aren’t XO‑specific, but they show the pattern is real.

Why this matters for XO?

XO’s backup pipeline is unusually heavy for a Node application:

• large streaming buffers
• compression
• encryption
• S3 multipart uploads
• high concurrency
• long‑lived async chains

This is exactly the kind of workload that tends to surface V8 memory issues that don’t appear in typical web servers or CLIs.

And since Node 20 goes EOL in April 2026, XO will eventually need to run reliably on Node 22/24 or an alternative runtime.
So the more accurate framing is:
This is not a kernel OOM.
This is a Node heap OOM, confirmed by the logs.
Node 22/24 are not globally unstable, but they do have documented memory regressions and behavior changes.
XO’s backup workload is heavy enough to expose those issues.
Even Node 20 shows a slow leak in XOA, which strongly suggests a XO + Node interaction, not a Node‑only problem.
Investigating Node 22/24 memory behavior is still worthwhile because XO recommends using the latest LTS.
Long‑term, XO may need fixes, profiling, or architectural adjustments to run reliably on future Node versions.

tunamagur0 created this issue in nodejs/node

closed Memory leak due to increasing RetainedMaps size in V8 (Fixed upstream) #57412

[MajorP93]

Okay, to update on my findings:

According to the log lines

[40:0x2e27d000] 312864931 ms: Scavenge 2011.2 (2033.4) -> 2005.3 (2033.6) MB, pooled: 0 MB, 2.31 / 0.00 ms  (average mu = 0.257, current mu = 0.211) task;
[40:0x2e27d000] 312867125 ms: Mark-Compact (reduce) **2023.6** (2044.9) -> **2000.5 (2015.5)** MB, pooled: 0 MB, 83.33 / 0.62 ms  (+ 1867.4 ms in 298 steps since start of marking, biggest step 19.4 ms, walltime since start of marking 2194 ms) (average mu = 0.333,
FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory

The default heap size seems to be 2GB. I read some Node documentation regarding heap size and understood that configured heap size is honored on a per-process basis.
XO backup seems to spawn multiple node processes (workers) which is why I figured the value I previously set as an attempt to fix my issue was too high (max-old-space-size=6144), 6GB can cause OOM quickly when multiple Node processes are being spawned.

For now I added 512MB to the default heap which results in my heap totaling to 2.5GB.
I hope that this will suffice for my backup jobs to not fail as my log clearly indicated the cause of the Node OOM was the heap ceiling being touched.

If it was caused by Node 22+ RSS there would be other log entries.

Also I was thinking a bit more about what @pilow said and I think I observed something similar.
Due to the "interrupted" issue already occurring a few weeks back I checked "htop" once in a while on my XO VM and noticed that after backup jobs completed the RAM usage not really goes down to the value it was sitting before.
After a fresh reboot of my XO VM RAM usage sits at around 1GB.
During backups it showed around 6GB of 10GB total being used.
After backups finished XO VM was sitting at around 5GB of RAM.
So yeah maybe there is a memory leak somewhere after all.

Anyhow I will keep monitoring this and see if the increased heap makes backup jobs more robust.

Would still be interesting to hear something from XO team in this regard.

Best regards
MajorP

[Pilow]

@MajorP93 here are some screenshots of my XOA RAM

(lost before sunday stats since I crashed my host in RPU this weekend...)

you can clearly see RAM crawling and beeing dumped each reboot.

here is one of my XOA Proxies (4 in total, they totally offload backups from my main XOA)

there is also a slope of RAM crawling up... little spikes are overhead when backups are ongoing.

I started to reboot XOA+all 4 proxxies every morning.