Limit number of generated BPF programs #2141
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viktormalik
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Feb 8, 2022
src/ast/passes/codegen_llvm.cpp
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| std::to_string(probe_count_) + | ||
| " BPF programs, which exceeds the current limit of " + | ||
| std::to_string(bpftrace_.max_programs_) + | ||
| " and it could take a long time.\n" |
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I think we can leave this out. I'm more worried about the amount of system resources you end up stealing if you attach so many programs than it taking long
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Changed "take a long time" to "take a lot of resources" in docs. Should be ready for another review.
| probe_count_ += matches.size(); | ||
| if (probe_count_ > bpftrace_.max_programs_) | ||
| { | ||
| throw std::runtime_error( |
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Using LOG(FATAL) here might be nicer for the end user
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I wouldn't say, the exception is caught and translated to LOG(ERROR) while LOG(FATAL) will terminate the program with SIGABRT which is not very user-friendly.
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In some cases (e.g. when using the "probe" builtin), the number of generated BPF functions may be very large which may cause BPFtrace to hang. This change prevents that by setting a limit on the number of generated BPF functions. The limit can be changed using the BPFTRACE_MAX_BPF_PROGS environment variable.
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Originates from this comment.
In some cases (e.g. when using the
probebuiltin), the number of generated BPF functions may be very large which may cause bpftrace to hang. This is a safeguard that sets a limit of 512 BPF functions by default. The limit can be changed using theBPFTRACE_MAX_BPF_PROGSenvironment variable.Checklist
man/adoc/bpftrace.adocand if needed indocs/reference_guide.mdCHANGELOG.md