v8-heapsnapshot
v1.3.1
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Reads a v8 heapsnapshot
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v8-heapsnapshot
A npm module to parse and work with v8's heapsnapshots.
For more information about heapsnapshots see here
Install
Just add the package v8-heapsnapshot
to your dependencies.
npm install --save v8-heapsnapshot
How to use
JavaScript:
var v8hs = require("v8-heapsnapshot")
v8hs.parseSnapshotFromFile()
.then(function(snapshot) {
// all nodes
snapshot.nodes
// all edges
snapshot.edges
// the global object
snapshot.global
// a list of loaded modules
snapshot.modules
// find node by id
snapshot.findNodeById(id)
})
TypeScript:
import {parseSnapshotFromFile} from 'v8-heapsnapshot'
// ...
const snapshot = await v8hs.parseSnapshotFromFile()
// all nodes
snapshot.nodes
// all edges
snapshot.edges
// the global object
snapshot.global
// a list of loaded modules
snapshot.modules
// find node by id
snapshot.findNodeById(id)
API
Parse a Snapshot
Parse the Snapshot with the data already in memory:
async function parseSnapshot(stream: fs.ReadStream): Promise<Snapshot>
async function parseSnapshot(json: string): Promise<Snapshot>
async function parseSnapshot(obj: Object): Promise<Snapshot>
Read a file and parse the Snapshot:
/* option type is the same as fs.createReadStream's option parameter */
async function parseSnapshotFromFile(filename: fs.PathLike, options?): Promise<Snapshot>
Work with a Snapshot
A snapshot consists of nodes and edges.
The node of the global object (name: global /
) and the list of modules (name: Module
) are already found.
Use findNodeById
to find a node by its id.
interface Snapshot {
// Whether the field detached is present in Node
readonly hasDetachedness: boolean
readonly nodes: Node[]
readonly edges: Edge[]
readonly global: Node
readonly modules: Node[]
findNodeById(id: number): Node | undefined
}
You can then go through the snapshot graph:
export interface Node {
readonly type: NodeType
readonly name: string
readonly id: number
readonly self_size: number
readonly edge_count: number
readonly trace_node_id: number
// Indicates whether the node is unreachable from the window object.
// Might be undefined on older heap snapshots.
readonly detached?: boolean
readonly out_edges: Edge[]
readonly in_edges: Edge[]
toLongString(): string
// print the node and `deep` reffered nodes to console
print(deep?: number): void
}
export interface Edge {
readonly type: EdgeType
readonly name: string | number
readonly from: Node
readonly to: Node
toLongString(): string
}