exc: The JSON element does not have the requested type. (HeapProfiler::Error) about heap-profiler

[casperisfine]

Hello. I've seen similar issues in the past, particular in apps using Sidekiq on Ruby 3.0 because of a Ruby bug.

I assume one of the line may be corrupted.

You can get rid of these broken lines with heap-profiler clean path/to/file.json. See f7da0ad

But I'd also love if you could share the broken lines, so I could see if it's another Ruby bug I could fix. You can use the same File.readlines { JSON.parse } snippet to identify them.

[casperisfine]

Hum, actually, re-reading the error, the issue isn't strictly a JSON syntax error, but that one of the values isn't of the expected type.

To identify it you may need to bisect the heap.

[casperisfine]

Also was the heap dump generated with 3.2.1? Or is that just your local ruby?

[theSoenke]

@casperisfine thanks a lot. heap-profiler clean fixed the problem! I've been using Ruby 3.2.1 both where the heap was created and locally. In general it also seems to be a valid JSON file and parsing it line by line seemed to work.

Here's also a diff before and after the clean step:

1494103d1494102
< 80, "flags":{"wb_protected":true, "old":true, "uncollectible":true, "marked":true}}
1494123d1494121
< {"address":"0x7f9d07934990", "type":"STRING", "shape_id":12, "slot_size":80, "class":"0x7f9d093aed98", "frozen":true, "embedded":true, "fstring":true, "bytesize":23, "value":"indeterminate_check_box", "encoding":"UTF-8"

[casperisfine]

Hum, the first like is clearly only the half-end of a JSON object, I wonder what happened here.

The second line seem fine except that it's not terminated. I wonder if it might be a flushing issue of some sort.