Fork - Podflare

curl -X POST https://api.podflare.ai/v1/sandboxes/$SID/fork \
  -H 'content-type: application/json' \
  -d '{"n": 5}'

children = parent.fork(n=5)
try:
    results = [c.run_code(plan) for c, plan in zip(children, plans)]
finally:
    for c in children:
        c.close()

const children = await parent.fork(5);
try {
  const results = await Promise.all(
    children.map((c, i) => c.runCode(plans[i]))
  );
} finally {
  for (const c of children) await c.close();
}

{
  "children": [
    "sbx_a1ac8f28d473413585d8f4f425bcc2b1",
    "sbx_03cfbf63bb394575aefa4e6c62874998",
    "sbx_532288c716c8424cb8bb549e6ce2748b",
    "sbx_bca65926af5f4afcaa6b8f20a66845b2",
    "sbx_267b68883b41469fbda8973296767542"
  ]
}

POST

sandboxes

{id}

fork

curl -X POST https://api.podflare.ai/v1/sandboxes/$SID/fork \
  -H 'content-type: application/json' \
  -d '{"n": 5}'

children = parent.fork(n=5)
try:
    results = [c.run_code(plan) for c, plan in zip(children, plans)]
finally:
    for c in children:
        c.close()

const children = await parent.fork(5);
try {
  const results = await Promise.all(
    children.map((c, i) => c.runCode(plans[i]))
  );
} finally {
  for (const c of children) await c.close();
}

{
  "children": [
    "sbx_a1ac8f28d473413585d8f4f425bcc2b1",
    "sbx_03cfbf63bb394575aefa4e6c62874998",
    "sbx_532288c716c8424cb8bb549e6ce2748b",
    "sbx_bca65926af5f4afcaa6b8f20a66845b2",
    "sbx_267b68883b41469fbda8973296767542"
  ]
}

string

required

Parent sandbox id.

int

default:"1"

Number of children to spawn. Range 1..=32.

curl -X POST https://api.podflare.ai/v1/sandboxes/$SID/fork \
  -H 'content-type: application/json' \
  -d '{"n": 5}'

children = parent.fork(n=5)
try:
    results = [c.run_code(plan) for c, plan in zip(children, plans)]
finally:
    for c in children:
        c.close()

const children = await parent.fork(5);
try {
  const results = await Promise.all(
    children.map((c, i) => c.runCode(plans[i]))
  );
} finally {
  for (const c of children) await c.close();
}

{
  "children": [
    "sbx_a1ac8f28d473413585d8f4f425bcc2b1",
    "sbx_03cfbf63bb394575aefa4e6c62874998",
    "sbx_532288c716c8424cb8bb549e6ce2748b",
    "sbx_bca65926af5f4afcaa6b8f20a66845b2",
    "sbx_267b68883b41469fbda8973296767542"
  ]
}

What children inherit

Each child starts from the parent’s state at the moment of snapshot:

Python REPL state — variables, imports, open files.
Filesystem — everything written to the parent’s rootfs so far.
Full VM memory — page-level CoW shared with siblings; divergence only costs the pages a child mutates.

Parent impact

Paused for ~80 ms during snapshot. Resume is automatic.
exec calls on the parent made after fork returns are NOT visible in children. Each child only sees pre-fork state.

Timing (Hetzner EX63)

n	Total `fork` latency
1	92 ms
2	102 ms
5	101 ms

Spawn cost is near-flat in N because children boot in parallel (~10 ms each) and the snapshot+merge happens once.

Requirements

Parent must be a pool-warm sandbox (or itself a fork child). Sandboxes created with custom RAM / rootfs skip the warm pool and cannot be forked — fork will return 500 on those.

Execute code Merge into

​What children inherit

​Parent impact

​Timing (Hetzner EX63)

​Requirements

What children inherit

Parent impact

Timing (Hetzner EX63)

Requirements