ProfileRecorderServer/Server.swift:338: Fatal error: Unexpectedly found nil while unwrapping an Optional value #43
Description
I'm registering the profile service into Consul with a health check so that list of targets to profile could be automatically determined.
Since HTTP check has no endpoint which returns 200, had to switch to a TCP session health check, which unfortunately causes this force unwrap to fail:
ProfileRecorderServer/Server.swift:338: Fatal error: Unexpectedly found nil while unwrapping an Optional value
(lldb) p child.channel
warning: TypeSystemSwiftTypeRef::GetNumChildren: had to engage SwiftASTContext fallback for type $s8NIOPosix27MultiThreadedEventLoopGroupCD(NIOPosix.SocketChannel) 0x0000000bd8709dc0 {
NIOPosix.BaseStreamSocketChannel<NIOPosix.Socket> = {
NIOPosix.BaseSocketChannel<NIOPosix.Socket> = {
parent = 0x0000000bd5e27900 {
NIOPosix.BaseSocketChannel<NIOPosix.ServerSocket> ={...}
backlog = 128{...}
group = 0x0000000bd84b45f0{...}
}
socket = 0x0000000bd6bcdde0 {
NIOPosix.BaseSocket ={...}
}
closePromise = {
futureResult = 0x0000000bd6a2eb20{...}
}
selectableEventLoop = 0x0000000bd5c9a3e0 {
_selector = 0x0000000bd8902fd0{...}
thread = 0x0000000bd58a63d0{...}
_pendingTaskPop = false{...}
scheduledTaskCounter = 0x0000000bd65a69e0{...}
_scheduledTasks ={...}
_immediateTasks ={...}
_uniqueID ={...}
tasksCopy = 0 values{...}
_succeededVoidFuture = 0x0000000bd58359f0{...}
canBeShutdownIndividually = false{...}
_tasksLock ={...}
_externalStateLock ={...}
internalState = runningAndAcceptingNewRegistrations{...}
externalState = open{...}
bufferPool = 0x0000000bd88d78c0{...}
msgBufferPool = 0x0000000bd65a69c0{...}
_parentGroup = 0x0000000bd84b45f0{...}
promiseCreationStoreLock ={...}
_promiseCreationStore = 2 key/value pairs{...}
metricsDelegate = nil{...}
lastTickEndTime ={...}
}
_offEventLoopLock = {
_storage = 0x0000000bd9418140{...}
}
isActiveAtomic = 0x0000000bd80052a0 (__storage = Swift.Bool.AtomicRepresentation @ 0x0000000bd80052b0)
socketDescription = "BaseSocket { fd=172 }"
readPending = true
pendingConnect = nil
recvBufferPool = {
_buffer = some{...}
_buffers = 0 values{...}
_lastUsedIndex = 0{...}
capacity = 4{...}
recvAllocator ={...}
_mayGrow = false{...}
}
maxMessagesPerRead = 4
inFlushNow = false
autoRead = true
_pipeline = 0x0000000bd6609ea0 {
head = nil{...}
tail = nil{...}
idx = 8{...}
destroyed = true{...}
eventLoop = 0x0000000bd5c9a3e0{...}
_channel = nil{...}
}
_addressCache = {
local = nil{...}
remote = nil{...}
}
_bufferAllocatorCache = {
malloc = 90 a0 63 0a 01 00 00 00{...}
realloc = d0 a0 63 0a 01 00 00 00{...}
free ={...}
memcpy ={...}
}
interestedEvent = (rawValue = 1)
lifecycleManager = {
eventLoop = 0x0000000bd5c9a3e0{...}
isActiveAtomic = 0x0000000bd80052a0{...}
hasSeenEOFNotification = true{...}
supportsReconnect = false{...}
currentState = closed{...}
}
bufferAllocator = {
malloc = 90 a0 63 0a 01 00 00 00{...}
realloc = d0 a0 63 0a 01 00 00 00{...}
free ={...}
memcpy ={...}
}
}
connectTimeoutScheduled = none
allowRemoteHalfClosure = false
inputShutdown = false
outputShutdown = false
pendingWrites = 0x0000000bd5521d60 {
state = {
pendingWrites ={...}
bytes = 0{...}
}
bufferPool = 0x0000000bd88d78c0 {
maxSize = 16{...}
elements = 0 values{...}
}
waterMark = (low = 32768, high = 65536)
channelWritabilityFlag = 0x0000000bd8004de0 (__storage = Swift.Bool.AtomicRepresentation @ 0x0000000bd8004df0)
publishedWritability = true
writeSpinCount = 16
isOpen = false
outboundCloseState = closed
}
}
connectTimeout = nil
}
The crash can be reproduced with simple connect and immediate close:
python3 -c "import socket; s=socket.socket(); s.connect(('localhost',59349)); s.close()"