runtime/tools/heapsnapshot/README

Examples:

# Load
load <file>

# Show named sets / known variables
info

# Find live objects
closure roots

# or give a name
all = closure roots

# Look into the object
stats all

# Filter lists from "all" into "lists"
lists = filter all _List

# Find empty lists into "empty-lists"
empty-lists = dfilter lists ==0

# Who's using the empty lists?
users empty-lists

# print that info (from $0 in this case as we didn't give it a name but it was
# the first one we didn't give a name)
stat $0

# Filter more
empty-growable-lists = filter (users empty-lists) _GrowableList

# Print
stats empty-growable-lists

# Who's using them?
retainers empty-growable-lists

# Look into strings next
strings = filter all String

# What's inside the strings
dstats strings

# Who's pointing to the big strings?
retainers (dfilter strings >=1024)

# Small strings
small-strings = dfilter strings <100

# See them
dstats small-strings

# Who's retaining the string "foo"
f = dfilter small-strings foo
retainters f

# Find stuff with specific field
hasField = filter all :specificField
stats closure hasField :specificField
foo = follow hasField :specificField
stats closure foo

# Stop the closure search if going into specific files
stats closure foo ^file1.dart ^file2.dart ^file3.dart