debug Namespace

The debug API gives you access to several non-standard RPC methods, which will allow you to inspect, debug and set certain debugging flags during runtime.

debug_accountRange

Enumerates all accounts at a given block with paging capability. maxResults are returned in the page and the items have keys that come after the start key (hashed address).

If incompletes is false, then accounts for which the key preimage (i.e: the address) doesn't exist in db are skipped. NB: geth by default does not store preimages.

debug_backtraceAt

Sets the logging backtrace location. When a backtrace location is set and a log message is emitted at that location, the stack of the goroutine executing the log statement will be printed to stderr.

The location is specified as <filename>:<line>.

Example:

> debug.backtraceAt("server.go:443")

debug_blockProfile

Turns on block profiling for the given duration and writes profile data to disk. It uses a profile rate of 1 for most accurate information. If a different rate is desired, set the rate and write the profile manually using debug_writeBlockProfile.

debug_chaindbCompact

Flattens the entire key-value database into a single level, removing all unused slots and merging all keys.

debug_chaindbProperty

Returns leveldb properties of the key-value database.

debug_cpuProfile

Turns on CPU profiling for the given duration and writes profile data to disk.

debug_dbAncient

Retrieves an ancient binary blob from the freezer. The freezer is a collection of append-only immutable files. The first argument kind specifies which table to look up data from. The list of all table kinds are as follows:

debug_dbAncients

Returns the number of ancient items in the ancient store.

debug_dbGet

Returns the raw value of a key stored in the database.

debug_dumpBlock

Retrieves the state that corresponds to the block number and returns a list of accounts (including storage and code).

Example:

> debug.dumpBlock(10)
{
    fff7ac99c8e4feb60c9750054bdc14ce1857f181: {
      balance: "49358640978154672",
      code: "",
      codeHash: "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470",
      nonce: 2,
      root: "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
      storage: {}
    },
    fffbca3a38c3c5fcb3adbb8e63c04c3e629aafce: {
      balance: "3460945928",
      code: "",
      codeHash: "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470",
      nonce: 657,
      root: "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
      storage: {}
    }
  },
  root: "19f4ed94e188dd9c7eb04226bd240fa6b449401a6c656d6d2816a87ccaf206f1"
}

debug_freeOSMemory

Forces garbage collection

debug_freezeClient

Forces a temporary client freeze, normally when the server is overloaded. Available as part of LES light server.

debug_gcStats

Returns garbage collection statistics.

See https://golang.org/pkg/runtime/debug/#GCStats for information about the fields of the returned object.

debug_getAccessibleState

Returns the first number where the node has accessible state on disk. This is the post-state of that block and the pre-state of the next block. The (from, to) parameters are the sequence of blocks to search, which can go either forwards or backwards.

Note: to get the last state pass in the range of blocks in reverse, i.e. (last, first).

debug_getBadBlocks

Returns a list of the last 'bad blocks' that the client has seen on the network and returns them as a JSON list of block-hashes.

debug_getRawBlock

Retrieves and returns the RLP encoded block by number.

References: RLP

debug_getRawHeader

Returns an RLP-encoded header.

debug_getRawTransaction

Returns the bytes of the transaction.

debug_getModifiedAccountsByHash

Returns all accounts that have changed between the two blocks specified. A change is defined as a difference in nonce, balance, code hash, or storage hash. With one parameter, returns the list of accounts modified in the specified block.

debug_getModifiedAccountsByNumber

Returns all accounts that have changed between the two blocks specified. A change is defined as a difference in nonce, balance, code hash or storage hash.

debug_getRawReceipts

Returns the consensus-encoding of all receipts in a single block.

debug_goTrace

Turns on Go runtime tracing for the given duration and writes trace data to disk.

debug_intermediateRoots

Executes a block (bad- or canon- or side-), and returns a list of intermediate roots: the stateroot after each transaction.

debug_memStats

Returns detailed runtime memory statistics.

See https://golang.org/pkg/runtime/#MemStats for information about the fields of the returned object.

debug_mutexProfile

Turns on mutex profiling for nsec seconds and writes profile data to file. It uses a profile rate of 1 for most accurate information. If a different rate is desired, set the rate and write the profile manually.

debug_preimage

Returns the preimage for a sha3 hash, if known.

debug_printBlock

Retrieves a block and returns its pretty printed form.

debug_setBlockProfileRate

Sets the rate (in samples/sec) of goroutine block profile data collection. A non-zero rate enables block profiling, setting it to zero stops the profile. Collected profile data can be written using debug_writeBlockProfile.

debug_setGCPercent

Sets the garbage collection target percentage. A negative value disables garbage collection.

debug_setHead

Sets the current head of the local chain by block number. Note, this is a destructive action and may severely damage your chain. Use with extreme caution.

References: Ethash

debug_setMutexProfileFraction

Sets the rate of mutex profiling.

debug_setTrieFlushInterval

Configures how often in-memory state tries are persisted to disk. The interval needs to be in a format parsable by a time.Duration. Note that the interval is not wall-clock time. Rather it is accumulated block processing time after which the state should be flushed. For example the value 0s will essentially turn on archive mode. If set to 1h, it means that after one hour of effective block processing time, the trie would be flushed. If one block takes 200ms, a flush would occur every 5*3600=18000 blocks. The default interval for mainnet is 1h.

Note: this configuration will not be persisted through restarts.

debug_stacks

Returns a printed representation of the stacks of all goroutines. Note that the web3 wrapper for this method takes care of the printing and does not return the string.

debug_standardTraceBlockToFile

When JS-based tracing (see below) was first implemented, the intended usecase was to enable long-running tracers that could stream results back via a subscription channel. This method works a bit differently. (For full details, see PR)

This means that this method is only 'useful' for callers who control the node -- at least sufficiently to be able to read the artefacts from the filesystem after the fact.

The method can be used to dump a certain transaction out of a given block:

> debug.standardTraceBlockToFile("0x0bbe9f1484668a2bf159c63f0cf556ed8c8282f99e3ffdb03ad2175a863bca63", {txHash:"0x4049f61ffbb0747bb88dc1c85dd6686ebf225a3c10c282c45a8e0c644739f7e9", disableMemory:true})
["/tmp/block_0x0bbe9f14-14-0x4049f61f-099048234"]

Or all txs from a block:

> debug.standardTraceBlockToFile("0x0bbe9f1484668a2bf159c63f0cf556ed8c8282f99e3ffdb03ad2175a863bca63", {disableMemory:true})
["/tmp/block_0x0bbe9f14-0-0xb4502ea7-409046657", "/tmp/block_0x0bbe9f14-1-0xe839be8f-954614764", "/tmp/block_0x0bbe9f14-2-0xc6e2052f-542255195", "/tmp/block_0x0bbe9f14-3-0x01b7f3fe-209673214", "/tmp/block_0x0bbe9f14-4-0x0f290422-320999749", "/tmp/block_0x0bbe9f14-5-0x2dc0fb80-844117472", "/tmp/block_0x0bbe9f14-6-0x35542da1-256306111", "/tmp/block_0x0bbe9f14-7-0x3e199a08-086370834", "/tmp/block_0x0bbe9f14-8-0x87778b88-194603593", "/tmp/block_0x0bbe9f14-9-0xbcb081ba-629580052", "/tmp/block_0x0bbe9f14-10-0xc254381a-578605923", "/tmp/block_0x0bbe9f14-11-0xcc434d58-405931366", "/tmp/block_0x0bbe9f14-12-0xce61967d-874423181", "/tmp/block_0x0bbe9f14-13-0x05a20b35-267153288", "/tmp/block_0x0bbe9f14-14-0x4049f61f-606653767", "/tmp/block_0x0bbe9f14-15-0x46d473d2-614457338", "/tmp/block_0x0bbe9f14-16-0x35cf5500-411906321", "/tmp/block_0x0bbe9f14-17-0x79222961-278569788", "/tmp/block_0x0bbe9f14-18-0xad84e7b1-095032683", "/tmp/block_0x0bbe9f14-19-0x4bd48260-019097038", "/tmp/block_0x0bbe9f14-20-0x1517411d-292624085", "/tmp/block_0x0bbe9f14-21-0x6857e350-971385904", "/tmp/block_0x0bbe9f14-22-0xbe3ae2ca-236639695"]

Files are created in a temp-location, with the naming standard block_<blockhash:4>-<txindex>-<txhash:4>-<random suffix>. Each opcode immediately streams to file, with no in-geth buffering aside from whatever buffering the os normally does.

On the server side, it also adds some more info when regenerating historical state, namely, the reexec-number if required historical state is not available is encountered, so a user can experiment with increasing that setting. It also prints out the remaining block until it reaches target:

The options is as follows:

type StdTraceConfig struct {
  *vm.LogConfig
  Reexec *uint64
  TxHash *common.Hash
}

debug_standardTraceBadBlockToFile

This method is similar to debug_standardTraceBlockToFile, but can be used to obtain info about a block which has been rejected as invalid (for some reason).

debug_startCPUProfile

Turns on CPU profiling indefinitely, writing to the given file.

debug_startGoTrace

Starts writing a Go runtime trace to the given file.

debug_stopCPUProfile

Stops an ongoing CPU profile.

debug_stopGoTrace

Stops writing the Go runtime trace.

debug_storageRangeAt

Returns the storage at the given block height and transaction index. The result can be paged by providing a maxResult to cap the number of storage slots returned as well as specifying the offset via keyStart (hash of storage key).

debug_traceBadBlock

Returns the structured logs created during the execution of EVM against a block pulled from the pool of bad ones and returns them as a JSON object. For the second parameter see TraceConfig reference.

debug_traceBlock

The traceBlock method will return a full stack trace of all invoked opcodes of all transaction that were included in this block. Note, the parent of this block must be present or it will fail. For the second parameter see TraceConfig reference.

References: RLP

Example:

> debug.traceBlock("0xblock_rlp")
[
  {
    txHash: "0xabba...",
    result: {
      gas: 85301,
      returnValue: "",
      structLogs: [{
          depth: 1,
          error: "",
          gas: 162106,
          gasCost: 3,
          memory: null,
          op: "PUSH1",
          pc: 0,
          stack: [],
          storage: {}
      },
      /* snip */
      {
          depth: 1,
          error: "",
          gas: 100000,
          gasCost: 0,
          memory: ["0000000000000000000000000000000000000000000000000000000000000006", "0000000000000000000000000000000000000000000000000000000000000000", "0000000000000000000000000000000000000000000000000000000000000060"],
          op: "STOP",
          pc: 120,
          stack: ["00000000000000000000000000000000000000000000000000000000d67cbec9"],
          storage: {
            0000000000000000000000000000000000000000000000000000000000000004: "8241fa522772837f0d05511f20caa6da1d5a3209000000000000000400000001",
            0000000000000000000000000000000000000000000000000000000000000006: "0000000000000000000000000000000000000000000000000000000000000001",
            f652222313e28459528d920b65115c16c04f3efc82aaedc97be59f3f377c0d3f: "00000000000000000000000002e816afc1b5c0f39852131959d946eb3b07b5ad"
          }
      }]
    }
  },
  {
    txHash: "0xacca...",
    result: {
      /* snip */
    }
  }
]

debug_traceBlockByNumber

Similar to debug_traceBlock, traceBlockByNumber accepts a block number and will replay the block that is already present in the database. For the second parameter see TraceConfig reference.

References: RLP

debug_traceBlockByHash

Similar to debug_traceBlock, traceBlockByHash accepts a block hash and will replay the block that is already present in the database. For the second parameter see TraceConfig reference.

References: RLP

debug_traceBlockFromFile

Similar to debug_traceBlock, traceBlockFromFile accepts a file containing the RLP of the block. For the second parameter see TraceConfig reference.

References: RLP

debug_traceCall

The debug_traceCall method lets you run an eth_call within the context of the given block execution using the final state of parent block as the base. The first argument (just as in eth_call) is a transaction object. The block can be specified either by hash or by number as the second argument. The trace can be configured similar to debug_traceTransaction, see TraceCallConfig. The method returns the same output as debug_traceTransaction.

TraceCallConfig

TraceCallConfig is a superset of TraceConfig, providing additional arguments in addition to those provided by TraceConfig:

Example:

No specific call options:

> debug.traceCall(null, "0x0")
{
  failed: false,
  gas: 53000,
  returnValue: "",
  structLogs: []
}

Tracing a call with a destination and specific sender, disabling the storage and memory output (less data returned over RPC)

> debug.traceCall(
  {
    from: "0xdeadbeef29292929192939494959594933929292",
    to: "0xde929f939d939d393f939393f93939f393929023",
    gas: "0x7a120",
    data: "0xf00d4b5d00000000000000000000000001291230982139282304923482304912923823920000000000000000000000001293123098123928310239129839291010293810"
  },
  "latest",
  { disableStorage: true, disableMemory: true }
);

It is possible to supply 'overrides' for both state-data (accounts/storage) and block data (number, timestamp etc). In the example below, a call which executes NUMBER is performed, and the overridden number is placed on the stack:

> debug.traceCall(
  {
    from: eth.accounts[0],
    value: "0x1",
    gasPrice: "0xffffffff",
    gas: "0xffff",
    input: "0x43"
  },
  "latest",
  {
    "blockOverrides": {"number": "0x50"}
  })
{
  failed: false,
  gas: 53018,
  returnValue: "",
  structLogs: [{
      depth: 1,
      gas: 12519,
      gasCost: 2,
      op: "NUMBER",
      pc: 0,
      stack: []
  }, {
      depth: 1,
      gas: 12517,
      gasCost: 0,
      op: "STOP",
      pc: 1,
      stack: ["0x50"]
  }]
}

Curl example:

> curl -H "Content-Type: application/json" -X POST  localhost:8545 --data '{"jsonrpc":"2.0","method":"debug_traceCall","params":[null, "pending"],"id":1}'
{"jsonrpc":"2.0","id":1,"result":{"gas":53000,"failed":false,"returnValue":"","structLogs":[]}}

debug_traceChain

Returns the structured logs created during the execution of EVM between two blocks (excluding start) as a JSON object. This endpoint must be invoked via debug_subscribe as follows:

const res = provider.send('debug_subscribe', ['traceChain', '0x3f3a2a', '0x3f3a2b'])`

please refer to the subscription page for more details.

debug_traceTransaction

OBS In most scenarios, debug.standardTraceBlockToFile is better suited for tracing!

The traceTransaction debugging method will attempt to run the transaction in the exact same manner as it was executed on the network. It will replay any transaction that may have been executed prior to this one before it will finally attempt to execute the transaction that corresponds to the given hash.

TraceConfig

In addition to the hash of the transaction you may give it a secondary optional argument, which specifies the options for this specific call. The possible options are:

Geth comes with a bundle of built-in tracers, each providing various data about a transaction. The tracer field can be set to either a JS expression or the name of a built-in or custom native tracer. If tracer is left empty the opcode logger will be chosen as default.

TraceConfig object has more fields that are specific to the opcode logger and which will be ignored when tracer field is set to any value. For configuration of built-in tracers refer to their respective documentation. The fields are:

Example:

> debug.traceTransaction("0x2059dd53ecac9827faad14d364f9e04b1d5fe5b506e3acc886eff7a6f88a696a")
{
  gas: 85301,
  returnValue: "",
  structLogs: [{
      depth: 1,
      error: "",
      gas: 162106,
      gasCost: 3,
      memory: null,
      op: "PUSH1",
      pc: 0,
      stack: [],
      storage: {}
  },
    /* snip */
  {
      depth: 1,
      error: "",
      gas: 100000,
      gasCost: 0,
      memory: ["0000000000000000000000000000000000000000000000000000000000000006", "0000000000000000000000000000000000000000000000000000000000000000", "0000000000000000000000000000000000000000000000000000000000000060"],
      op: "STOP",
      pc: 120,
      stack: ["00000000000000000000000000000000000000000000000000000000d67cbec9"],
      storage: {
        0000000000000000000000000000000000000000000000000000000000000004: "8241fa522772837f0d05511f20caa6da1d5a3209000000000000000400000001",
        0000000000000000000000000000000000000000000000000000000000000006: "0000000000000000000000000000000000000000000000000000000000000001",
        f652222313e28459528d920b65115c16c04f3efc82aaedc97be59f3f377c0d3f: "00000000000000000000000002e816afc1b5c0f39852131959d946eb3b07b5ad"
      }
  }]

debug_verbosity

Sets the logging verbosity ceiling. Log messages with level up to and including the given level will be printed.

The verbosity of individual packages and source files can be raised using debug_vmodule.

debug_vmodule

Sets the logging verbosity pattern.

Examples:

If you want to see messages from a particular Go package (directory) and all subdirectories, use:

> debug.vmodule("eth/*=6")

If you want to restrict messages to a particular package (e.g. p2p) but exclude subdirectories, use:

> debug.vmodule("p2p=6")

If you want to see log messages from a particular source file, use

> debug.vmodule("server.go=6")

You can compose these basic patterns. If you want to see all output from peer.go in a package below eth (eth/peer.go, eth/downloader/peer.go) as well as output from package p2p at level <= 5, use:

debug.vmodule('eth/*/peer.go=6,p2p=5');

debug_writeBlockProfile

Writes a goroutine blocking profile to the given file.

debug_writeMemProfile

Writes an allocation profile to the given file. Note that the profiling rate cannot be set through the API, it must be set on the command line using the --pprof.memprofilerate flag.

debug_writeMutexProfile

Writes a goroutine blocking profile to the given file.