JQ scripts for analyzing heap dumps

script.sh

# Sort by memsize from first 50 lines of dump (can be just with `cat` command)
head -50 input.json | jq --slurp '[.[] | {address: .address, type: .type, file: .file, line: .line, method: .method, memsize: .memsize }] | sort_by(.memsize) | map([.address, .type, .file, "\(.line)", .method, "\(.memsize)"] | join(" ")) | reverse' | head -20

# Group objects by type-class-struct-name, count them, count sum of their memsize and sort them by count
# Useful when you didn't trace allocations
cat input_file | jq --slurp '[.[] | {type: "\(.type) \(.class) \(.struct) \(.name)", memsize: .memsize}] | group_by(.type) | map(reduce .[] as $item ({type: .[0].type, memsize: .[0].memsize, count: 0}; {type: .type, memsize: (.memsize + $item.memsize), count: (.count + 1)})) | sort_by(.count) | map(["\(.count)", "\(.memsize)", .type] | join(" : ")) | reverse' > output_file

# Group objects by allocation file-line, count them and their sum of memsize and sort by memsize
cat input_file | jq --slurp '[.[] | {address: .address, type: .type, file: "\(.file)\(.line)", value: .value, method: .method, memsize: .memsize }] | group_by(.file) | map(reduce .[] as $item ({file: .[0].file, type: .[0].type, count: 0, memsize: 0}; {file: .file, type: .type, count: (.count + 1), memsize: (.memsize + $item.memsize)})) | sort_by(.memsize) | map(["\(.count)", "\(.memsize)", .type, .file] | join(" ")) | reverse' > output_file